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"""
| :class:`pandas.Series` functions and operators implementations in SDC
| Also, it contains Numba internal operators which are required for Series type handling
"""

import numba
import numpy
import operator
import pandas
import math
import sys

from numba.core.errors import TypingError
from numba.core.typing import signature
from numba.extending import intrinsic
from numba import types
from numba.core import cgutils
from numba.np import numpy_support
from numba.typed import List, Dict
from numba import prange
from numba.np.arraymath import get_isnan
from pandas.core.indexing import IndexingError

import sdc
import sdc.datatypes.common_functions as common_functions
from sdc.utilities.sdc_typing_utils import (TypeChecker, check_index_is_numeric, check_types_comparable,
                                            find_common_dtype_from_numpy_dtypes, has_literal_value,
                                            has_python_value,
                                            sdc_old_index_types,
                                            find_index_common_dtype,
                                            )
from sdc.datatypes.indexes import *
from sdc.datatypes.common_functions import (sdc_arrays_argsort, sdc_reindex_series, _sdc_internal_join)
from sdc.datatypes.hpat_pandas_rolling_types import (
    gen_sdc_pandas_rolling_overload_body, sdc_pandas_rolling_docstring_tmpl)
from sdc.datatypes.hpat_pandas_series_rolling_types import _hpat_pandas_series_rolling_init
from sdc.datatypes.hpat_pandas_stringmethods_types import StringMethodsType
from sdc.datatypes.hpat_pandas_getitem_types import SeriesGetitemAccessorType
from sdc.hiframes.pd_series_type import SeriesType
from sdc.str_arr_type import (StringArrayType, string_array_type)
from sdc.str_arr_ext import (str_arr_is_na, str_arr_set_na, num_total_chars,
                             pre_alloc_string_array, cp_str_list_to_array,
                             create_str_arr_from_list, str_arr_set_na_by_mask,
                             str_list_to_array)
from sdc.utilities.utils import to_array, sdc_overload, sdc_overload_method, sdc_overload_attribute
from sdc import sdc_autogenerated
from sdc.functions import numpy_like
from sdc.hiframes.api import isna
from sdc.datatypes.hpat_pandas_groupby_functions import init_series_groupby
from sdc.utilities.prange_utils import parallel_chunks
from sdc.extensions.indexes.indexes_generic import sdc_indexes_join_outer, sdc_fix_indexes_join
from sdc.set_ext import build_set

from .pandas_series_functions import apply
from .pandas_series_functions import map as _map


@sdc_overload(operator.getitem)
def hpat_pandas_series_accessor_getitem(self, idx):
    """
    Pandas Series operator :attr:`pandas.Series.__getitem__` implementation
    for methods `pandas.Series.iloc`, `pandas.Series.loc`, `pandas.Series.iat`, `pandas.Series.at`

    Parameters
    ----------
    self: :class:`pandas.Series`
        input Series
    other: :obj:`pandas.Series`, :obj:`int` or :obj:`float`, :obj:`slice`, :obj:`list`
        input arg

    Returns
    -------
    :class:`pandas.Series` or a value of :obj:`pandas.Series.dtype`
        returns object
    """

    _func_name = 'Operator getitem().'

    if not isinstance(self, SeriesGetitemAccessorType):
        return None

    accessor = self.accessor.literal_value

    if accessor == 'iloc':
        if isinstance(idx, (types.List, types.Array, types.SliceType)):
            def hpat_pandas_series_iloc_list_slice_impl(self, idx):
                result_data = self._series._data[idx]
                result_index = self._series.index[idx]
                return pandas.Series(data=result_data, index=result_index, name=self._series._name)

            return hpat_pandas_series_iloc_list_slice_impl

        if isinstance(idx, (int, types.Integer)):
            def hpat_pandas_series_iloc_impl(self, idx):
                return self._series._data[idx]

            return hpat_pandas_series_iloc_impl

        def hpat_pandas_series_iloc_callable_impl(self, idx):
            index = numpy.asarray(list(map(idx, self._series._data)))
            return pandas.Series(
                data=self._series._data[index],
                index=self._series.index[index],
                name=self._series._name
            )

        return hpat_pandas_series_iloc_callable_impl

        raise TypingError('{} The index must be an Integer, Slice or List of Integer or a callable.\
                    Given: {}'.format(_func_name, idx))

    if accessor == 'iat':
        if isinstance(idx, (int, types.Integer)):
            def hpat_pandas_series_iat_impl(self, idx):
                return self._series._data[idx]

            return hpat_pandas_series_iat_impl

        raise TypingError('{} The index must be a Integer. Given: {}'.format(_func_name, idx))

    if accessor == 'loc':
        # Note: Loc return Series
        # Note: Loc slice and callable with String is not implemented
        # Note: Loc slice without start is not supported
        min_int64 = numpy.iinfo('int64').min
        max_int64 = numpy.iinfo('int64').max
        index_is_positional = isinstance(self.series.index, PositionalIndexType)
        if isinstance(idx, types.SliceType) and not index_is_positional:
            def hpat_pandas_series_loc_slice_impl(self, idx):
                series = self._series
                index = series.index
                start_position = len(index)
                stop_position = 0
                max_diff = 0
                min_diff = 0
                start_position_inc = len(index)
                start_position_dec = len(index)
                stop_position_inc = 0
                stop_position_dec = 0
                idx_start = idx.start
                idx_stop = idx.stop
                for i in numba.prange(len(index)):
                    if index[i] >= idx_start:
                        start_position_inc = min(start_position_inc, i)
                    if index[i] <= idx_start:
                        start_position_dec = min(start_position_dec, i)
                    if index[i] <= idx_stop:
                        stop_position_inc = max(stop_position_inc, i)
                    if index[i] >= idx_stop:
                        stop_position_dec = max(stop_position_dec, i)
                    if i > 0:
                        max_diff = max(max_diff, index[i] - index[i - 1])
                        min_diff = min(min_diff, index[i] - index[i - 1])

                if max_diff*min_diff < 0:
                    raise ValueError("Index must be monotonic increasing or decreasing")

                if max_diff > 0:
                    start_position = start_position_inc
                    stop_position = stop_position_inc
                    if idx_stop < index[0]:
                        return pandas.Series(data=series._data[:0], index=series._index[:0], name=series._name)
                else:
                    start_position = start_position_dec
                    stop_position = stop_position_dec if idx.stop != max_int64 else len(index)
                    if idx_stop > index[0] and idx_stop != max_int64:
                        return pandas.Series(data=series._data[:0], index=series._index[:0], name=series._name)

                stop_position = min(stop_position + 1, len(index))

                if (
                    start_position >= len(index) or stop_position <= 0 or stop_position <= start_position
                ):
                    return pandas.Series(data=series._data[:0], index=series._index[:0], name=series._name)

                return pandas.Series(data=series._data[start_position:stop_position],
                                     index=index[start_position:stop_position],
                                     name=series._name)

            return hpat_pandas_series_loc_slice_impl

        if isinstance(idx, types.SliceType) and index_is_positional:
            def hpat_pandas_series_loc_slice_noidx_impl(self, idx):
                max_slice = sys.maxsize
                start = idx.start
                stop = idx.stop
                if idx.stop == max_slice:
                    stop = max_slice - 1
                result_data = self._series._data[start:stop+1]
                result_index = numpy.arange(start, stop + 1)
                return pandas.Series(data=result_data, index=result_index, name=self._series._name)

            return hpat_pandas_series_loc_slice_noidx_impl

        if isinstance(idx, (types.Array, types.List)):
            def hpat_pandas_series_loc_array_impl(self, idx):
                index = self._series.index
                data = self._series._data
                size = len(index)
                data_res = []
                index_res = []
                for value in idx:
                    mask = numpy.zeros(shape=size, dtype=numpy.bool_)
                    for i in numba.prange(size):
                        mask[i] = index[i] == value
                    data_res.extend(data[mask])
                    index_res.extend(index[mask])

                return pandas.Series(data=data_res, index=index_res, name=self._series._name)

            return hpat_pandas_series_loc_array_impl

        if isinstance(idx, (int, types.Integer, types.UnicodeType, types.StringLiteral)):
            def hpat_pandas_series_loc_impl(self, idx):
                index = self._series.index
                mask = numpy.empty(len(self._series._data), numpy.bool_)
                for i in numba.prange(len(index)):
                    mask[i] = index[i] == idx
                return pandas.Series(data=self._series._data[mask], index=index[mask], name=self._series._name)

            return hpat_pandas_series_loc_impl

        raise TypingError('{} The index must be an Number, Slice, String, List, Array or a callable.\
                          Given: {}'.format(_func_name, idx))

    if accessor == 'at':
        if isinstance(idx, (int, types.Integer, types.UnicodeType, types.StringLiteral)):
            def hpat_pandas_series_at_impl(self, idx):
                index = self._series.index
                count = 0
                mask = numpy.empty(len(self._series._data), numpy.bool_)
                for i in numba.prange(len(index)):
                    mask[i] = index[i] == idx
                    if mask[i] == True:  # noqa
                        count += 1
                if count == 0:  # noqa
                    raise ValueError("Index is not in the Series")
                return self._series._data[mask]

            return hpat_pandas_series_at_impl

        raise TypingError('{} The index must be a Number or String. Given: {}'.format(_func_name, idx))

    raise TypingError('{} Unknown accessor. Only "loc", "iloc", "at", "iat" are supported.\
                      Given: {}'.format(_func_name, accessor))


@sdc_overload(operator.getitem)
def hpat_pandas_series_getitem(self, idx):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************
    Pandas API: pandas.Series.getitem

    Get value(s) of Series by key.

    Limitations
    -----------
    Supported ``key`` can be one of the following:
        - Integer scalar, e.g. :obj:`series[0]`
        - An array or a list, e.g. :obj:`series[0,2,5]`
        - A list of booleans, e.g. :obj:`series[True,False]`
        - A slice, e.g. :obj:`series[2:5]`
        - Another series

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_getitem/series_getitem_scalar_single_result.py
       :language: python
       :lines: 32-
       :caption: Getting Pandas Series elements. Returns single value.
       :name: ex_series_getitem

    .. command-output:: python ./series/series_getitem/series_getitem_scalar_single_result.py
       :cwd: ../../../examples

    .. literalinclude:: ../../../examples/series/series_getitem/series_getitem_scalar_multiple_result.py
       :language: python
       :lines: 34-
       :caption: Getting Pandas Series elements. Returns multiple value.
       :name: ex_series_getitem

    .. command-output:: python ./series/series_getitem/series_getitem_scalar_multiple_result.py
       :cwd: ../../../examples

    .. literalinclude:: ../../../examples/series/series_getitem/series_getitem_slice.py
       :language: python
       :lines: 35-
       :caption: Getting Pandas Series elements by slice.
       :name: ex_series_getitem

    .. command-output:: python ./series/series_getitem/series_getitem_slice.py
       :cwd: ../../../examples

    .. literalinclude:: ../../../examples/series/series_getitem/series_getitem_bool_array.py
       :language: python
       :lines: 37-
       :caption: Getting Pandas Series elements by array of booleans.
       :name: ex_series_getitem

    .. command-output:: python ./series/series_getitem/series_getitem_bool_array.py
       :cwd: ../../../examples

    .. literalinclude:: ../../../examples/series/series_getitem/series_getitem_series.py
       :language: python
       :lines: 36-
       :caption: Getting Pandas Series elements by another Series.
       :name: ex_series_getitem

    .. command-output:: python ./series/series_getitem/series_getitem_series.py
       :cwd: ../../../examples

    .. seealso::
        :ref:`Series.setitem <pandas.Series.setitem>`
            Set value to Series by index
        :ref:`Series.loc <pandas.Series.loc>`
            Access a group of rows and columns by label(s) or a boolean array.
        :ref:`Series.iloc <pandas.Series.iloc>`
            Purely integer-location based indexing for selection by position.
        :ref:`Series.at <pandas.Series.at>`
            Access a single value for a row/column label pair.
        :ref:`Series.iat <pandas.Series.iat>`
            Access a single value for a row/column pair by integer position.
        :ref:`DataFrame.getitem <pandas.DataFrame.getitem>`
            Get data from a DataFrame by indexer.
        :ref:`DataFrame.setitem <pandas.DataFrame.setitem>`
            Set value to DataFrame by index
        :ref:`DataFrame.loc <pandas.DataFrame.loc>`
            Access a group of rows and columns by label(s) or a boolean array.
        :ref:`DataFrame.iloc <pandas.DataFrame.iloc>`
            Purely integer-location based indexing for selection by position.
        :ref:`DataFrame.at <pandas.DataFrame.at>`
            Access a single value for a row/column label pair.
        :ref:`DataFrame.iat <pandas.DataFrame.iat>`
            Access a single value for a row/column pair by integer position.

    .. todo:: Fix SDC behavior and add the expected output of the > python ./series_getitem.py to the docstring

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series operator :attr:`pandas.Series.__getitem__` implementation

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_getitem*
    """

    _func_name = 'Operator getitem().'

    if not isinstance(self, SeriesType):
        return None

    # Note: Getitem return Series
    index_is_positional = isinstance(self.index, PositionalIndexType)
    index_is_numeric = isinstance(self.index.dtype, types.Number)
    index_is_string = isinstance(self.index.dtype, types.UnicodeType)

    if (
        isinstance(idx, types.Number) and index_is_numeric or
        (isinstance(idx, (types.UnicodeType, types.StringLiteral)) and index_is_string)
    ):
        def hpat_pandas_series_getitem_index_impl(self, idx):
            index = self._index
            mask = numpy.empty(len(self._data), numpy.bool_)
            for i in numba.prange(len(index)):
                mask[i] = index[i] == idx
            return pandas.Series(data=self._data[mask], index=index[mask], name=self._name)

        return hpat_pandas_series_getitem_index_impl

    if (isinstance(idx, types.Integer) and index_is_string):
        def hpat_pandas_series_idx_impl(self, idx):
            return self._data[idx]

        return hpat_pandas_series_idx_impl

    if isinstance(idx, types.SliceType):
        # Return slice for str values not implement
        def hpat_pandas_series_getitem_idx_slice_impl(self, idx):
            return pandas.Series(data=self._data[idx], index=self.index[idx], name=self._name)

        return hpat_pandas_series_getitem_idx_slice_impl

    if (isinstance(idx, (types.List, types.Array))
            and isinstance(idx.dtype, types.Boolean)):
        def hpat_pandas_series_getitem_idx_list_impl(self, idx):

            if len(self) != len(idx):
                raise IndexError('Boolean index has wrong length')

            return pandas.Series(
                data=numpy_like.getitem_by_mask(self._data, idx),
                index=numpy_like.getitem_by_mask(self.index, idx),
                name=self._name
            )

        return hpat_pandas_series_getitem_idx_list_impl

    # idx is Series and it's index is any, idx.dtype is Boolean
    if (isinstance(idx, SeriesType) and isinstance(idx.dtype, types.Boolean)):

        positional_indexes = (isinstance(self.index, PositionalIndexType)
                              and isinstance(idx.index, PositionalIndexType))
        if not check_types_comparable(self.index, idx.index):
            msg = '{} The index of boolean indexer is not comparable to Series index.' + \
                  ' Given: self.index={}, idx.index={}'
            raise TypingError(msg.format(_func_name, self.index, idx.index))

        def _series_getitem_idx_bool_indexer_impl(self, idx):

            # TO-DO: replace sdc_reindex_series with reindex methods and move this logic to impl
            # for specific index types (needs proper index type instead of types.none as index)
            if positional_indexes == True:  # noqa
                if len(self) > len(idx):
                    msg = "Unalignable boolean Series provided as indexer " + \
                          "(index of the boolean Series and of the indexed object do not match)."
                    raise IndexingError(msg)

                self_index = self.index
                reindexed_idx = idx
            else:
                self_index = self.index
                reindexed_idx = sdc_reindex_series(idx._data, idx.index, idx._name, self_index)

            return pandas.Series(
                data=numpy_like.getitem_by_mask(self._data, reindexed_idx._data),
                index=numpy_like.getitem_by_mask(self_index, reindexed_idx._data),
                name=self._name
            )

        return _series_getitem_idx_bool_indexer_impl

    # idx is Series and it's index is PositionalIndex, idx.dtype is not Boolean
    if (isinstance(idx, SeriesType) and index_is_positional
            and not isinstance(idx.data.dtype, (types.Boolean, bool))):
        def hpat_pandas_series_getitem_idx_list_impl(self, idx):
            idx_data = idx._data
            self_data = self._data
            res = numpy.copy(self._data[:len(idx_data)])
            index = numpy.arange(len(self_data))
            for i in numba.prange(len(res)):
                for j in numba.prange(len(index)):
                    if j == idx_data[i]:
                        res[i] = self_data[j]
            return pandas.Series(data=res, index=index[idx_data], name=self._name)
        return hpat_pandas_series_getitem_idx_list_impl

    # idx is Series and it's index is not PositionalIndex, idx.dtype is not Boolean
    if (isinstance(idx, SeriesType) and not isinstance(self.index, PositionalIndexType)
            and not isinstance(idx.data.dtype, (types.Boolean, bool))):
        def hpat_pandas_series_getitem_idx_series_impl(self, idx):
            index = self.index
            data = self._data
            size = len(index)
            data_res = []
            index_res = []
            for value in idx._data:
                mask = numpy.zeros(shape=size, dtype=numpy.bool_)
                for i in numba.prange(size):
                    mask[i] = index[i] == value

                data_res.extend(data[mask])
                index_res.extend(index[mask])

            return pandas.Series(data=data_res, index=index_res, name=self._name)

        return hpat_pandas_series_getitem_idx_series_impl


    raise TypingError('{} The index must be an Number, Slice, String, Boolean Array or a Series.\
                    Given: {}'.format(_func_name, idx))


@sdc_overload(operator.setitem)
def sdc_pandas_series_setitem(self, idx, value):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************
    Pandas API: pandas.Series.setitem

    Set value to Series by index

    Limitations
    -----------
       - Not supported for idx as a string slice, e.g. S['a':'f'] = value
       - Not supported for string series
       - Not supported for a case of setting value for non existing index
       - Not supported for cases when setting causes change of the Series dtype

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_setitem_int.py
       :language: python
       :lines: 27-
       :caption: Setting Pandas Series elements
       :name: ex_series_setitem

    .. command-output:: python ./series/series_setitem_int.py
       :cwd: ../../../examples

    .. literalinclude:: ../../../examples/series/series_setitem_slice.py
       :language: python
       :lines: 27-
       :caption: Setting Pandas Series elements by slice
       :name: ex_series_setitem

    .. command-output:: python ./series/series_setitem_slice.py
       :cwd: ../../../examples

    .. literalinclude:: ../../../examples/series/series_setitem_series.py
       :language: python
       :lines: 27-
       :caption: Setting Pandas Series elements by series
       :name: ex_series_setitem

    .. command-output:: python ./series/series_setitem_series.py
       :cwd: ../../../examples

    .. seealso::
            :ref:`Series.getitem <pandas.Series.getitem>`
                Get value(s) of Series by key.
            :ref:`Series.loc <pandas.Series.loc>`
                Access a group of rows and columns by label(s) or a boolean array.
            :ref:`Series.iloc <pandas.Series.iloc>`
                Purely integer-location based indexing for selection by position.
            :ref:`Series.at <pandas.Series.at>`
                Access a single value for a row/column label pair.
            :ref:`Series.iat <pandas.Series.iat>`
                Access a single value for a row/column pair by integer position.
            :ref:`DataFrame.getitem <pandas.DataFrame.getitem>`
                Get data from a DataFrame by indexer.
            :ref:`DataFrame.setitem <pandas.DataFrame.setitem>`
                Set value to DataFrame by index
            :ref:`DataFrame.loc <pandas.DataFrame.loc>`
                Access a group of rows and columns by label(s) or a boolean array.
            :ref:`DataFrame.iloc <pandas.DataFrame.iloc>`
                Purely integer-location based indexing for selection by position.
            :ref:`DataFrame.at <pandas.DataFrame.at>`
                Access a single value for a row/column label pair.
            :ref:`DataFrame.iat <pandas.DataFrame.iat>`
                Access a single value for a row/column pair by integer position.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series operator :attr:`pandas.Series.set` implementation

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_setitem*
    """

    _func_name = 'Operator setitem().'
    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not (isinstance(idx, (types.Number, types.UnicodeType, types.SliceType, types.Array, SeriesType))):
        ty_checker.raise_exc(idx, 'scalar, Slice, Array or Series', 'idx')

    all_supported_scalar_types = (types.Number, types.UnicodeType, types.Boolean)
    if not (isinstance(value, all_supported_scalar_types) or isinstance(value, (SeriesType, types.Array))):
        ty_checker.raise_exc(value, 'scalar, Array or Series', 'value')

    if not check_types_comparable(self, value):
        msg = '{} The value and Series data must be comparable. Given: self.dtype={}, value={}'
        raise TypingError(msg.format(_func_name, self.dtype, value))

    # idx is not necessarily of the same dtype as self.index, e.g. it might be a Boolean indexer or a Slice
    if not (check_types_comparable(idx, self.index)
            or isinstance(idx, (types.Integer, types.SliceType))
            or (isinstance(idx, (SeriesType, types.Array)) and isinstance(idx.dtype, (types.Integer, types.Boolean)))):
        msg = '{} The idx is not comparable to Series index, not a Boolean or integer indexer or a Slice. ' + \
              'Given: self.index={}, idx={}'
        raise TypingError(msg.format(_func_name, self.index, idx))

    value_is_series = isinstance(value, SeriesType)
    value_is_array = isinstance(value, types.Array)

    # for many cases pandas setitem assigns values along positions in self._data
    # not considering Series index, so a common implementation exists
    idx_is_boolean_array = isinstance(idx, types.Array) and isinstance(idx.dtype, types.Boolean)
    idx_is_boolean_series = isinstance(idx, SeriesType) and isinstance(idx.dtype, types.Boolean)
    idx_and_self_index_comparable = check_types_comparable(self.index, idx)
    self_index_is_positional = isinstance(self.index, PositionalIndexType)
    idx_index_is_positional = isinstance(idx, SeriesType) and isinstance(idx.index, PositionalIndexType)
    assign_along_positions = ((self_index_is_positional
                               or isinstance(idx, types.SliceType)
                               or not idx_and_self_index_comparable)
                              and not idx_is_boolean_series
                              and not idx_is_boolean_array)

    idx_is_scalar = isinstance(idx, (types.Number, types.UnicodeType))
    if assign_along_positions or idx_is_scalar:

        idx_is_numeric_or_boolean_series = (isinstance(idx, SeriesType)
                                            and isinstance(idx.dtype, (types.Number, types.Boolean)))
        assign_via_idx_mask = idx_is_scalar and idx_and_self_index_comparable
        assign_via_idx_values = (self_index_is_positional and idx_index_is_positional
                                 or idx_is_numeric_or_boolean_series and not idx_and_self_index_comparable)

        def sdc_pandas_series_setitem_no_reindexing_impl(self, idx, value):

            if assign_via_idx_mask == True:  # noqa
                # FIXME_Numba#5157: using asarray since eq impl for index types returns list
                _idx = numpy.asarray(self._index == idx)
            elif assign_via_idx_values == True:  # noqa
                _idx = idx.values
            else:
                _idx = idx

            _value = value._data if value_is_series == True else value  # noqa
            self._data[_idx] = _value
            return self

        return sdc_pandas_series_setitem_no_reindexing_impl

    if (idx_is_boolean_array or idx_is_boolean_series) and value_is_series:

        if not check_types_comparable(self.index, value.index):
            msg = '{} The self and value indexes must be comparable. Given: self.dtype={}, value.dtype={}'
            raise TypingError(msg.format(_func_name, self.index, value.index))

        _, indexes_common_dtype = find_index_common_dtype(self.index, value.index)

    if idx_is_boolean_array:

        def sdc_pandas_series_setitem_idx_bool_array_align_impl(self, idx, value):

            series_data = self._data  # FIXME_Numba#6960
            # if idx is a Boolean array (and value is a series) it's used as a mask for self.index
            # and filtered indexes are looked in value.index, and if found corresponding value is set
            if value_is_series == True:  # noqa
                value_index, self_index = value.index, self.index
                unique_value_indices, unique_self_indices = build_set(value_index), build_set(self_index)

                # pandas behaves differently if value.index has duplicates and if it has no
                # in case of duplicates in value.index assignment is made via positions
                # in case there are no duplicates, value.index is used as reindexer
                self_index_has_duplicates = len(unique_self_indices) != len(self_index)
                value_index_has_duplicates = len(unique_value_indices) != len(value_index)
                if (self_index_has_duplicates or value_index_has_duplicates):
                    series_data[idx] = value._data
                else:
                    map_index_to_position = Dict.empty(
                        key_type=indexes_common_dtype,
                        value_type=types.int32
                    )
                    for i, index_value in enumerate(value_index):
                        map_index_to_position[index_value] = types.int32(i)

                    # such iterative setitem on a StringArray will be inefficient
                    # TODO: refactor this when str_arr setitem is fully supported
                    for i in numba.prange(len(self_index)):
                        if idx[i]:
                            self_index_value = self_index[i]
                            if self_index_value in map_index_to_position:
                                series_data[i] = value._data[map_index_to_position[self_index_value]]
                            else:
                                sdc.hiframes.join.setitem_arr_nan(series_data, i)

            else:
                # if value has no index - nothing to reindex and assignment is made along positions set by idx mask
                series_data[idx] = value

            return self

        return sdc_pandas_series_setitem_idx_bool_array_align_impl

    elif idx_is_boolean_series:

        def sdc_pandas_series_setitem_idx_bool_series_align_impl(self, idx, value):

            self_index, idx_index = self.index, idx.index
            # FIXME: for now just use sorted, as == is not implemented for sets of unicode strings
            if (sorted(self_index) != sorted(idx_index)):
                msg = "Unalignable boolean Series provided as indexer " + \
                      "(index of the boolean Series and of the indexed object do not match)"
                raise ValueError(msg)

            # if idx is a Boolean Series it's data is used as a mask for it's index
            # and filtered indexes are either looked in value.index (if value is a Series)
            # or in self.index (if value is scalar or array)
            filtered_idx_indices = idx_index[idx._data]
            filtered_idx_indices_set = build_set(filtered_idx_indices)
            if value_is_series == True:  # noqa

                if len(filtered_idx_indices_set) != len(filtered_idx_indices):
                    raise ValueError("cannot reindex from a duplicate axis")

                map_self_index_to_position = Dict.empty(
                    key_type=indexes_common_dtype,
                    value_type=types.int32
                )
                for i, index_value in enumerate(self_index):
                    map_self_index_to_position[index_value] = types.int32(i)

                value_index = value.index
                map_value_index_to_position = Dict.empty(
                    key_type=indexes_common_dtype,
                    value_type=types.int32
                )
                for i, index_value in enumerate(value_index):
                    map_value_index_to_position[index_value] = types.int32(i)

                # for all index values in filtered index assign element of value with this index
                # to element of self with this index
                for i in numba.prange(len(filtered_idx_indices)):
                    idx_index_value = filtered_idx_indices[i]
                    if idx_index_value in map_value_index_to_position:
                        self_index_pos = map_self_index_to_position[idx_index_value]
                        value_index_pos = map_value_index_to_position[idx_index_value]
                        self._data[self_index_pos] = value._data[value_index_pos]
                    else:
                        sdc.hiframes.join.setitem_arr_nan(self._data, map_self_index_to_position[idx_index_value])
            else:
                # use filtered index values to create a set mask, then make assignment to self
                # using this mask (i.e. the order of filtered indices in self.index does not matter)
                self_index_size = len(self_index)
                set_mask = numpy.zeros(self_index_size, dtype=numpy.bool_)
                for i in numba.prange(self_index_size):
                    if self_index[i] in filtered_idx_indices_set:
                        set_mask[i] = True
                self._data[set_mask] = value

            return self

        return sdc_pandas_series_setitem_idx_bool_series_align_impl

    elif isinstance(idx, (SeriesType, types.Array)) and idx_and_self_index_comparable:

        # idx is numeric Series or array comparable with self.index, hence reindexing is possible
        if isinstance(self.index.dtype, types.Number):

            idx_is_series = isinstance(idx, SeriesType)
            value_is_scalar = not (value_is_series or value_is_array)
            def sdc_pandas_series_setitem_idx_int_series_align_impl(self, idx, value):

                # FIXME_Numba#6960: all changes of this commit are unnecessary - revert when resolved
                self_data = self._data
                self_index = self._index
                self_index_size = len(self_index)
                idx_size = len(idx)

                _idx = idx._data if idx_is_series == True else idx  # noqa
                _value = value._data if value_is_series == True else value  # noqa

                valid_indices = numpy.repeat(-1, self_index_size)
                for i in numba.prange(self_index_size):
                    for j in numpy.arange(idx_size):
                        if self_index[i] == _idx[j]:
                            valid_indices[i] = j

                valid_indices_positions = numpy.arange(self_index_size)[valid_indices != -1]
                valid_indices_masked = valid_indices[valid_indices != -1]

                indexes_found = self_index[valid_indices_positions]
                if len(numpy.unique(indexes_found)) != len(indexes_found):
                    raise ValueError("Reindexing only valid with uniquely valued Index objects")

                if len(valid_indices_masked) != idx_size:
                    raise KeyError("Reindexing not possible: idx has index not found in Series")

                if value_is_scalar == True:  # noqa
                    self_data[valid_indices_positions] = _value
                else:
                    self_data[valid_indices_positions] = numpy.take(_value, valid_indices_masked)

                return self

            return sdc_pandas_series_setitem_idx_int_series_align_impl

        elif isinstance(self.index.dtype, types.UnicodeType):

            def sdc_pandas_series_setitem_idx_str_series_align_impl(self, idx, value):

                map_index_to_position = Dict.empty(
                    key_type=types.unicode_type,
                    value_type=types.int32
                )
                for i, index_value in enumerate(self._index):
                    if index_value in map_index_to_position:
                        raise ValueError("Reindexing only valid with uniquely valued Index objects")
                    map_index_to_position[index_value] = types.int32(i)

                idx_data_size = len(idx._data)
                number_of_found = 0
                set_positions = numpy.empty(idx_data_size, dtype=types.int32)
                for i in numba.prange(len(idx._data)):
                    index_value = idx._data[i]
                    if index_value in map_index_to_position:
                        number_of_found += 1
                        set_positions[i] = map_index_to_position[index_value]

                if number_of_found != idx_data_size:
                    raise KeyError("Reindexing not possible: idx has index not found in Series")

                set_values = value if value_is_series == False else value._data  # noqa
                self._data[set_positions] = set_values

                return self

            return sdc_pandas_series_setitem_idx_str_series_align_impl

        else:  # self.index.dtype other than types.Number or types.Unicode
            return None

    return None


@sdc_overload_attribute(SeriesType, 'iloc')
def hpat_pandas_series_iloc(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.iloc

    Limitations
    -----------
    Iloc always returns Series.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_iloc/series_iloc_value.py
       :language: python
       :lines: 27-
       :caption: With a scalar integer.
       :name: ex_series_iloc

    .. command-output:: python ./series/series_iloc/series_iloc_value.py
       :cwd: ../../../examples

    .. literalinclude:: ../../../examples/series/series_iloc/series_iloc_slice.py
       :language: python
       :lines: 33-
       :caption: With a slice object.
       :name: ex_series_iloc

    .. command-output:: python ./series/series_iloc/series_iloc_slice.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`DataFrame.iat <pandas.DataFrame.iat>`
            Fast integer location scalar accessor.

        :ref:`DataFrame.loc <pandas.DataFrame.loc>`
            Purely label-location based indexer for selection by label.

        :ref:`Series.iloc <pandas.Series.iloc>`
            Purely integer-location based indexing for selection by position.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.iloc` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_iloc*
    """

    _func_name = 'Attribute iloc().'

    if not isinstance(self, SeriesType):
        raise TypingError('{} The object must be a pandas.series. Given: {}'.format(_func_name, self))

    def hpat_pandas_series_iloc_impl(self):
        return sdc.datatypes.hpat_pandas_getitem_types.series_getitem_accessor_init(self, 'iloc')

    return hpat_pandas_series_iloc_impl


@sdc_overload_attribute(SeriesType, 'loc')
def hpat_pandas_series_loc(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.loc

    Limitations
    -----------
    - Loc always returns Series.
    - Loc slice is supported only with numeric values and specified ``start``.
    - Loc callable is not supported yet.
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_loc/series_loc_single_result.py
       :language: python
       :lines: 32-
       :caption: With a scalar integer. Returns single value.
       :name: ex_series_loc

    .. command-output:: python ./series/series_loc/series_loc_single_result.py
       :cwd: ../../../examples

    .. literalinclude:: ../../../examples/series/series_loc/series_loc_multiple_result.py
       :language: python
       :lines: 34-
       :caption: With a scalar integer. Returns multiple value.
       :name: ex_series_loc

    .. command-output:: python ./series/series_loc/series_loc_multiple_result.py
       :cwd: ../../../examples

    .. literalinclude:: ../../../examples/series/series_loc/series_loc_slice.py
       :language: python
       :lines: 34-
       :caption: With a slice object. Returns multiple value.
       :name: ex_series_loc

    .. command-output:: python ./series/series_loc/series_loc_slice.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`DataFrame.at <pandas.DataFrame.at>`
            Access a single value for a row/column label pair.

        :ref:`DataFrame.iloc <pandas.DataFrame.iloc>`
            Access group of rows and columns by integer position(s).

        :ref:`DataFrame.xs <pandas.DataFrame.xs>`
            Returns a cross-section (row(s) or column(s)) from the Series/DataFrame.

        :ref:`Series.loc <pandas.Series.loc>`
            Access group of values using labels.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.loc` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_loc*
    """

    _func_name = 'Attribute loc().'

    if not isinstance(self, SeriesType):
        raise TypingError('{} The object must be a pandas.series. Given: {}'.format(_func_name, self))

    def hpat_pandas_series_loc_impl(self):
        return sdc.datatypes.hpat_pandas_getitem_types.series_getitem_accessor_init(self, 'loc')

    return hpat_pandas_series_loc_impl


@sdc_overload_attribute(SeriesType, 'iat')
def hpat_pandas_series_iat(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.iat

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_iat.py
       :language: python
       :lines: 27-
       :caption: Get value at specified index position.
       :name: ex_series_iat

    .. command-output:: python ./series/series_iat.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`DataFrame.at <pandas.DataFrame.at>`
            Access a single value for a row/column label pair.

        :ref:`DataFrame.loc <pandas.DataFrame.loc>`
            Purely label-location based indexer for selection by label.

        :ref:`DataFrame.iloc <pandas.DataFrame.iloc>`
            Access group of rows and columns by integer position(s).

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.iat` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_iat*
    """

    _func_name = 'Attribute iat().'

    if not isinstance(self, SeriesType):
        raise TypingError('{} The object must be a pandas.series. Given: {}'.format(_func_name, self))

    def hpat_pandas_series_iat_impl(self):
        return sdc.datatypes.hpat_pandas_getitem_types.series_getitem_accessor_init(self, 'iat')

    return hpat_pandas_series_iat_impl


@sdc_overload_attribute(SeriesType, 'at')
def hpat_pandas_series_at(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.at

    Limitations
    -----------
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_at/series_at_single_result.py
       :language: python
       :lines: 27-
       :caption: With a scalar integer. Returns single value.
       :name: ex_series_at

    .. command-output:: python ./series/series_at/series_at_single_result.py
       :cwd: ../../../examples

    .. literalinclude:: ../../../examples/series/series_at/series_at_multiple_result.py
       :language: python
       :lines: 27-
       :caption: With a scalar integer. Returns multiple value.
       :name: ex_series_at

    .. command-output:: python ./series/series_at/series_at_multiple_result.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`DataFrame.iat <pandas.DataFrame.iat>`
            Access a single value for a row/column pair by integer position.

        :ref:`DataFrame.loc <pandas.DataFrame.loc>`
            Access a group of rows and columns by label(s).

        :ref:`Series.at <pandas.Series.at>`
            Access a single value using a label.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.at` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_at*
    """

    _func_name = 'Attribute at().'

    if not isinstance(self, SeriesType):
        raise TypingError('{} The object must be a pandas.series. Given: {}'.format(_func_name, self))

    def hpat_pandas_series_at_impl(self):
        return sdc.datatypes.hpat_pandas_getitem_types.series_getitem_accessor_init(self, 'at')

    return hpat_pandas_series_at_impl


@sdc_overload_method(SeriesType, 'nsmallest')
def hpat_pandas_series_nsmallest(self, n=5, keep='first'):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.nsmallest

    Limitations
    -----------
    - Parameter ``keep`` is supported only with default value ``'first'``.
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_nsmallest.py
       :language: python
       :lines: 27-
       :caption: Returns the smallest n elements.
       :name: ex_series_nsmallest

    .. command-output:: python ./series/series_nsmallest.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.nlargest <pandas.Series.nlargest>`
            Get the n largest elements.

        :ref:`Series.sort_values <pandas.Series.sort_values>`
            Sort Series by values.

        :ref:`Series.head <pandas.Series.head>`
            Return the first n rows.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************

    Pandas Series method :meth:`pandas.Series.nsmallest` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_nsmallest*
    """

    _func_name = 'Method nsmallest().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(n, (types.Omitted, int, types.Integer)):
        ty_checker.raise_exc(n, 'int', 'n')

    if not isinstance(keep, (types.Omitted, str, types.UnicodeType, types.StringLiteral)):
        ty_checker.raise_exc(keep, 'str', 'keep')

    def hpat_pandas_series_nsmallest_impl(self, n=5, keep='first'):
        if keep != 'first':
            raise ValueError("Method nsmallest(). Unsupported parameter. Given 'keep' != 'first'")

        # mergesort is used for stable sorting of repeated values
        indices = numpy_like.argsort(self._data, kind='mergesort')[:max(n, 0)]

        return self.take(indices)

    return hpat_pandas_series_nsmallest_impl


@sdc_overload_method(SeriesType, 'nlargest')
def hpat_pandas_series_nlargest(self, n=5, keep='first'):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.nlargest

    Limitations
    -----------
    - Parameter ``keep`` is supported only with default value ``'first'``.
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_nlargest.py
       :language: python
       :lines: 27-
       :caption: Returns the largest n elements.
       :name: ex_series_nlargest

    .. command-output:: python ./series/series_nlargest.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.nsmallest <pandas.Series.nsmallest>`
            Get the n smallest elements.

        :ref:`Series.sort_values <pandas.Series.sort_values>`
            Sort Series by values.

        :ref:`Series.head <pandas.Series.head>`
            Return the first n rows.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************

    Pandas Series method :meth:`pandas.Series.nlargest` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_nlargest*
    """

    _func_name = 'Method nlargest().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(n, (types.Omitted, int, types.Integer)):
        ty_checker.raise_exc(n, 'int', 'n')

    if not isinstance(keep, (types.Omitted, str, types.UnicodeType, types.StringLiteral)):
        ty_checker.raise_exc(keep, 'str', 'keep')

    def hpat_pandas_series_nlargest_impl(self, n=5, keep='first'):
        if keep != 'first':
            raise ValueError("Method nlargest(). Unsupported parameter. Given 'keep' != 'first'")

        # data: [0, 1, -1, 1, 0] -> [1, 1, 0, 0, -1]
        # index: [0, 1,  2, 3, 4] -> [1, 3, 0, 4,  2] (not [3, 1, 4, 0, 2])
        # subtract 1 to ensure reverse ordering at boundaries
        indices = numpy_like.argsort(-self._data - 1, kind='mergesort')[:max(n, 0)]

        return self.take(indices)

    return hpat_pandas_series_nlargest_impl


@sdc_overload_attribute(SeriesType, 'shape')
def hpat_pandas_series_shape(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.shape

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_shape.py
       :language: python
       :lines: 27-
       :caption: Return a tuple of the shape of the underlying data.
       :name: ex_series_shape

    .. command-output:: python ./series/series_shape.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series attribute :attr:`pandas.Series.shape` implementation

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_series_shape1
    """

    _func_name = 'Attribute shape.'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    def hpat_pandas_series_shape_impl(self):
        return self._data.shape

    return hpat_pandas_series_shape_impl


@sdc_overload_method(SeriesType, 'std')
def hpat_pandas_series_std(self, axis=None, skipna=None, level=None, ddof=1, numeric_only=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.std

    Limitations
    -----------
    Parameters ``axis``, ``level`` and ``numeric_only`` are supported only with default value ``None``.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_std.py
       :language: python
       :lines: 27-
       :caption: Returns sample standard deviation over Series.
       :name: ex_series_std

    .. command-output:: python ./series/series_std.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.var <pandas.Series.var>`
            Returns unbiased variance over Series.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************

    Pandas Series method :meth:`pandas.Series.std` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_std
    """

    _func_name = 'Method std().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, types.Number):
        ty_checker.raise_exc(self.data, 'number', 'self.data')

    if not isinstance(skipna, (types.Omitted, types.Boolean, types.NoneType)) and skipna is not None:
        ty_checker.raise_exc(skipna, 'bool', 'skipna')

    if not isinstance(ddof, (types.Omitted, int, types.Integer)):
        ty_checker.raise_exc(ddof, 'int', 'ddof')

    if not isinstance(axis, (types.Omitted, types.NoneType)) and axis is not None:
        ty_checker.raise_exc(axis, 'None', 'axis')

    if not isinstance(level, (types.Omitted, types.NoneType)) and level is not None:
        ty_checker.raise_exc(level, 'None', 'level')

    if not isinstance(numeric_only, (types.Omitted, types.NoneType)) and numeric_only is not None:
        ty_checker.raise_exc(numeric_only, 'None', 'numeric_only')

    def hpat_pandas_series_std_impl(self, axis=None, skipna=None, level=None, ddof=1, numeric_only=None):
        var = self.var(axis=axis, skipna=skipna, level=level, ddof=ddof, numeric_only=numeric_only)
        return var ** 0.5

    return hpat_pandas_series_std_impl


@sdc_overload_attribute(SeriesType, 'values')
def hpat_pandas_series_values(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.values

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_values.py
       :language: python
       :lines: 27-
       :caption: Return Series as ndarray or ndarray-like depending on the dtype.
       :name: ex_series_values

    .. command-output:: python ./series/series_values.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.array <pandas.Series.array>`
            Reference to the underlying data.

        :ref:`Series.to_numpy <pandas.Series.to_numpy>`
            A NumPy array representing the underlying data.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series attribute 'values' implementation.

    .. only:: developer
        Test:  python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_values*
    """

    _func_name = 'Attribute values.'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    def hpat_pandas_series_values_impl(self):
        return self._data

    return hpat_pandas_series_values_impl


@sdc_overload_method(SeriesType, 'value_counts')
def hpat_pandas_series_value_counts(self, normalize=False, sort=True, ascending=False, bins=None, dropna=True):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.value_counts

    Limitations
    -----------
    - Parameters ``normalize`` and ``bins`` are currently unsupported.
    - Parameter ``dropna`` is unsupported for String Series.
    - Elements with the same count might appear in result in a different order than in Pandas.
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_value_counts.py
       :language: python
       :lines: 35-
       :caption: Getting the number of values excluding NaNs
       :name: ex_series_value_counts

    .. command-output:: python ./series/series_value_counts.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.count <pandas.Series.count>`

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.value_counts` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_value_counts*
    """

    _func_name = 'Method value_counts().'

    ty_checker = TypeChecker('Method value_counts().')
    ty_checker.check(self, SeriesType)

    if not isinstance(normalize, (types.Omitted, types.Boolean, bool)) and normalize is True:
        ty_checker.raise_exc(normalize, 'boolean', 'normalize')

    if not isinstance(sort, (types.Omitted, types.Boolean, bool)):
        ty_checker.raise_exc(sort, 'boolean', 'sort')

    if not isinstance(ascending, (types.Omitted, types.Boolean, bool)):
        ty_checker.raise_exc(ascending, 'boolean', 'ascending')

    if not isinstance(bins, (types.Omitted, types.NoneType)) and bins is not None:
        ty_checker.raise_exc(bins, 'boolean', 'bins')

    if not isinstance(dropna, (types.Omitted, types.Boolean, bool)):
        ty_checker.raise_exc(dropna, 'boolean', 'dropna')

    if isinstance(self.data, StringArrayType):
        def hpat_pandas_series_value_counts_str_impl(
                self, normalize=False, sort=True, ascending=False, bins=None, dropna=True):

            value_counts_dict = Dict.empty(
                key_type=types.unicode_type,
                value_type=types.intp
            )

            nan_counts = 0
            for i, value in enumerate(self._data):
                if str_arr_is_na(self._data, i):
                    if not dropna:
                        nan_counts += 1
                    continue

                value_counts_dict[value] = value_counts_dict.get(value, 0) + 1

            need_add_nan_count = not dropna and nan_counts

            values = [key for key in value_counts_dict]
            counts_as_list = [value_counts_dict[key] for key in value_counts_dict.keys()]
            values_len = len(values)

            if need_add_nan_count:
                # append a separate empty string for NaN elements
                values_len += 1
                values.append('')
                counts_as_list.append(nan_counts)

            counts = numpy.asarray(counts_as_list, dtype=numpy.intp)
            indexes_order = numpy.arange(values_len)
            if sort:
                indexes_order = numpy_like.argsort(counts)
                if not ascending:
                    indexes_order = indexes_order[::-1]

            counts_sorted = numpy.take(counts, indexes_order)
            values_sorted_by_count = [values[i] for i in indexes_order]

            # allocate the result index as a StringArray and copy values to it
            result_index = create_str_arr_from_list(values_sorted_by_count)
            if need_add_nan_count:
                # set null bit for StringArray element corresponding to NaN element (was added as last in values)
                index_previous_nan_pos = values_len - 1
                for i in numpy.arange(values_len):
                    if indexes_order[i] == index_previous_nan_pos:
                        str_arr_set_na(result_index, i)
                        break

            return pandas.Series(counts_sorted, index=result_index, name=self._name)

        return hpat_pandas_series_value_counts_str_impl

    elif isinstance(self.dtype, (types.Number, types.Boolean)):

        series_dtype = self.dtype
        def hpat_pandas_series_value_counts_number_impl(
                self, normalize=False, sort=True, ascending=False, bins=None, dropna=True):

            value_counts_dict = Dict.empty(
                key_type=series_dtype,
                value_type=types.intp
            )

            zero_counts = 0
            is_zero_found = False
            for value in self._data:
                if (dropna and numpy.isnan(value)):
                    continue

                # Pandas hash-based value_count_float64 function doesn't distinguish between
                # positive and negative zeros, hence we count zero values separately and store
                # as a key the first zero value found in the Series
                if not value:
                    zero_counts += 1
                    if not is_zero_found:
                        zero_value = value
                        is_zero_found = True
                    continue

                value_counts_dict[value] = value_counts_dict.get(value, 0) + 1

            if zero_counts:
                value_counts_dict[zero_value] = zero_counts

            unique_values = numpy.asarray(
                list(value_counts_dict),
                dtype=self._data.dtype
            )
            value_counts = numpy.asarray(
                [value_counts_dict[key] for key in value_counts_dict],
                dtype=numpy.intp
            )

            indexes_order = numpy.arange(len(value_counts))
            if sort:
                indexes_order = numpy_like.argsort(value_counts)
                if not ascending:
                    indexes_order = indexes_order[::-1]

            sorted_unique_values = numpy.take(unique_values, indexes_order)
            sorted_value_counts = numpy.take(value_counts, indexes_order)

            return pandas.Series(sorted_value_counts, index=sorted_unique_values, name=self._name)

        return hpat_pandas_series_value_counts_number_impl

    return None


@sdc_overload_method(SeriesType, 'var')
def hpat_pandas_series_var(self, axis=None, skipna=None, level=None, ddof=1, numeric_only=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.var

    Limitations
    -----------
    Parameters ``axis``, ``level`` and ``numeric_only`` are supported only with default value ``None``.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_var.py
       :language: python
       :lines: 27-
       :caption: Returns unbiased variance over Series.
       :name: ex_series_var

    .. command-output:: python ./series/series_var.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.std <pandas.Series.std>`
            Returns sample standard deviation over Series.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************

    Pandas Series method :meth:`pandas.Series.var` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_var
    """

    _func_name = 'Method var().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, types.Number):
        ty_checker.raise_exc(self.data, 'number', 'self.data')

    if not isinstance(skipna, (types.Omitted, types.Boolean, types.NoneType)) and skipna is not None:
        ty_checker.raise_exc(skipna, 'bool', 'skipna')

    if not isinstance(ddof, (types.Omitted, int, types.Integer)):
        ty_checker.raise_exc(ddof, 'int', 'ddof')

    if not isinstance(axis, (types.Omitted, types.NoneType)) and axis is not None:
        ty_checker.raise_exc(axis, 'None', 'axis')

    if not isinstance(level, (types.Omitted, types.NoneType)) and level is not None:
        ty_checker.raise_exc(level, 'None', 'level')

    if not isinstance(numeric_only, (types.Omitted, types.NoneType)) and numeric_only is not None:
        ty_checker.raise_exc(numeric_only, 'None', 'numeric_only')

    def hpat_pandas_series_var_impl(self, axis=None, skipna=None, level=None, ddof=1, numeric_only=None):
        if skipna is None:
            skipna = True

        self_data = self._data  # FIXME_Numba#6960
        if skipna:
            valuable_length = len(self_data) - numpy.sum(numpy.isnan(self_data))
            if valuable_length <= ddof:
                return numpy.nan

            return numpy_like.nanvar(self_data) * valuable_length / (valuable_length - ddof)

        if len(self_data) <= ddof:
            return numpy.nan

        return self_data.var() * len(self_data) / (len(self_data) - ddof)

    return hpat_pandas_series_var_impl


@sdc_overload_attribute(SeriesType, 'index')
def hpat_pandas_series_index(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.index

    Limitations
    -----------
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_index.py
       :language: python
       :lines: 27-
       :caption: The index (axis labels) of the Series.
       :name: ex_series_index

    .. command-output:: python ./series/series_index.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series attribute :attr:`pandas.Series.index` implementation

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_series_index1
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_series_index2
    """

    _func_name = 'Attribute index.'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    def hpat_pandas_series_index_impl(self):
        return self._index

    return hpat_pandas_series_index_impl


hpat_pandas_series_rolling = sdc_overload_method(SeriesType, 'rolling')(
    gen_sdc_pandas_rolling_overload_body(_hpat_pandas_series_rolling_init, SeriesType))
hpat_pandas_series_rolling.__doc__ = sdc_pandas_rolling_docstring_tmpl.format(
    ty='Series', ty_lower='series')


@sdc_overload_attribute(SeriesType, 'size')
def hpat_pandas_series_size(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.size

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_size.py
       :language: python
       :lines: 27-
       :caption: Return the number of elements in the underlying data.
       :name: ex_series_size

    .. command-output:: python ./series/series_size.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series attribute :attr:`pandas.Series.size` implementation

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_series_size
    """

    _func_name = 'Attribute size.'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    def hpat_pandas_series_size_impl(self):
        return len(self._data)

    return hpat_pandas_series_size_impl


@sdc_overload_attribute(SeriesType, 'str')
def hpat_pandas_series_str(self):
    """
    Pandas Series attribute :attr:`pandas.Series.str` implementation

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_hiframes.TestHiFrames.test_str_get
    """

    _func_name = 'Attribute str.'

    if not isinstance(self, SeriesType):
        raise TypingError('{} The object must be a pandas.series. Given: {}'.format(_func_name, self))

    if not isinstance(self.data.dtype, (types.List, types.UnicodeType)):
        msg = '{}  Can only use .str accessor with string values. Given: {}'
        raise TypingError(msg.format(_func_name, self.data.dtype))

    def hpat_pandas_series_str_impl(self):
        return pandas.core.strings.StringMethods(self)

    return hpat_pandas_series_str_impl


@sdc_overload_attribute(SeriesType, 'ndim')
def hpat_pandas_series_ndim(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.ndim

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_ndim.py
       :language: python
       :lines: 27-
       :caption: Number of dimensions of the underlying data, by definition 1.
       :name: ex_series_ndim

    .. command-output:: python ./series/series_ndim.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series attribute :attr:`pandas.Series.ndim` implementation

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_series_getattr_ndim
    """

    _func_name = 'Attribute ndim.'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    def hpat_pandas_series_ndim_impl(self):
        return 1

    return hpat_pandas_series_ndim_impl


@sdc_overload_attribute(SeriesType, 'T')
def hpat_pandas_series_T(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.T

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_T.py
       :language: python
       :lines: 27-
       :caption: Return the transpose, which is by definition self.
       :name: ex_series_T

    .. command-output:: python ./series/series_T.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series attribute :attr:`pandas.Series.T` implementation

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_series_getattr_T
    """

    _func_name = 'Attribute T.'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    def hpat_pandas_series_T_impl(self):
        return self._data

    return hpat_pandas_series_T_impl


@sdc_overload(len)
def hpat_pandas_series_len(self):
    """
    Pandas Series operator :func:`len` implementation

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_series_len
    """

    _func_name = 'Operator len().'

    if not isinstance(self, SeriesType):
        raise TypingError('{} The object must be a pandas.series. Given: {}'.format(_func_name, self))

    def hpat_pandas_series_len_impl(self):
        return len(self._data)

    return hpat_pandas_series_len_impl


@sdc_overload_method(SeriesType, 'astype')
def hpat_pandas_series_astype(self, dtype, copy=True, errors='raise'):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.astype

    Limitations
    -----------
    - Parameter ``copy`` is supported only with default value ``True``.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_astype.py
       :language: python
       :lines: 36-
       :caption: Cast a pandas object to a specified dtype.
       :name: ex_series_astype

    .. command-output:: python ./series/series_astype.py
       :cwd: ../../../examples

    .. seealso::

        `pandas.to_datetime
        <https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.to_datetime.html#pandas.to_datetime>`_
            Convert argument to datetime.

        `pandas.to_timedelta
        <https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.to_timedelta.html#pandas.to_timedelta>`_
            Convert argument to timedelta.

        `pandas.to_numeric
        <https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.to_numeric.html#pandas.to_numeric>`_
            Convert argument to a numeric type.

        `numpy.ndarray.astype
        <https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.astype.html#numpy.ndarray.astype>`_
            Copy of the array, cast to a specified type.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.astype` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_astype*
    """

    _func_name = 'Method astype().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(copy, (types.Omitted, bool, types.Boolean)):
        ty_checker.raise_exc(copy, 'bool', 'copy')

    if not (isinstance(dtype, (types.functions.NumberClass, types.Function, types.StringLiteral))):
        return None

    if (not isinstance(errors, (types.Omitted, str, types.UnicodeType, types.StringLiteral)) and
        errors in ('raise', 'ignore')):
        ty_checker.raise_exc(errors, 'str', 'errors')

    # Return npytypes.Array from npytypes.Array for astype(types.functions.NumberClass), example - astype(np.int64)
    # Return npytypes.Array from npytypes.Array for astype(types.StringLiteral), example - astype('int64')
    def hpat_pandas_series_astype_numba_impl(self, dtype, copy=True, errors='raise'):
        return pandas.Series(data=numpy_like.astype_no_inline(self._data, dtype), index=self._index, name=self._name)

    # Return self
    def hpat_pandas_series_astype_no_modify_impl(self, dtype, copy=True, errors='raise'):
        return pandas.Series(data=self._data, index=self._index, name=self._name)

    str_check = ((isinstance(dtype, types.Function) and dtype.typing_key == str) or
                 (isinstance(dtype, types.StringLiteral) and dtype.literal_value == 'str'))

    # Needs Numba astype impl support converting unicode_type to NumberClass and other types
    if isinstance(self.data, StringArrayType):
        if not str_check:
            if isinstance(dtype, types.functions.NumberClass) and errors == 'raise':
                raise TypingError(f'Needs Numba astype impl support converting unicode_type to {dtype}')
            if isinstance(dtype, types.StringLiteral) and errors == 'raise':
                try:
                    literal_value = numpy.dtype(dtype.literal_value)
                except TypeError:
                    pass  # Will raise the exception later
                else:
                    raise TypingError(f'Needs Numba astype impl support converting unicode_type to {literal_value}')
        else:
            return hpat_pandas_series_astype_no_modify_impl

    data_narr = isinstance(self.data, types.npytypes.Array)
    dtype_num_liter = isinstance(dtype, (types.functions.NumberClass, types.StringLiteral))

    if data_narr and dtype_num_liter or str_check:
        return hpat_pandas_series_astype_numba_impl

    if errors == 'raise':
        raise TypingError(f'{_func_name} The object must be a supported type. Given dtype: {dtype}')
    else:
        return hpat_pandas_series_astype_no_modify_impl


@sdc_overload_method(SeriesType, 'shift')
def hpat_pandas_series_shift(self, periods=1, freq=None, axis=0, fill_value=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.shift

    Limitations
    -----------
    Parameters ``freq`` and ``axis`` are supported only with default values ``None`` and ``0`` respectively.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_shift.py
       :language: python
       :lines: 36-
       :caption: Shift index by desired number of periods with an optional time freq.
       :name: ex_series_shift

    .. command-output:: python ./series/series_shift.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************

    Pandas Series method :meth:`pandas.Series.shift` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_shift*
    """

    _func_name = 'Method shift().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, types.Number):
        ty_checker.raise_exc(self.data.dtype, 'number', 'self.data.dtype')

    if not isinstance(fill_value, (types.Omitted, types.Number, types.NoneType)) and fill_value is not None:
        ty_checker.raise_exc(fill_value, 'number', 'fill_value')

    if not isinstance(freq, (types.Omitted, types.NoneType)) and freq is not None:
        ty_checker.raise_exc(freq, 'None', 'freq')

    if not isinstance(axis, (types.Omitted, int, types.Integer)) and not axis:
        ty_checker.raise_exc(axis, 'int', 'axis')

    fill_is_default = isinstance(fill_value, (types.Omitted, types.NoneType)) or fill_value is None
    series_np_dtype = [numpy_support.as_dtype(self.data.dtype)]
    fill_np_dtype = [numpy.float64 if fill_is_default else numpy_support.as_dtype(fill_value)]

    fill_dtype = types.float64 if fill_is_default else fill_value
    common_dtype = find_common_dtype_from_numpy_dtypes([], [self.data.dtype, fill_dtype])

    if fill_is_default:
        def hpat_pandas_series_shift_impl(self, periods=1, freq=None, axis=0, fill_value=None):
            if axis != 0:
                raise TypingError('Method shift(). Unsupported parameters. Given axis != 0')

            arr = numpy.empty(shape=len(self._data), dtype=common_dtype)
            if periods > 0:
                arr[:periods] = numpy.nan
                arr[periods:] = self._data[:-periods]
            elif periods < 0:
                arr[periods:] = numpy.nan
                arr[:periods] = self._data[-periods:]
            else:
                arr[:] = self._data

            return pandas.Series(data=arr, index=self._index, name=self._name)

        return hpat_pandas_series_shift_impl

    def hpat_pandas_series_shift_impl(self, periods=1, freq=None, axis=0, fill_value=None):
        if axis != 0:
            raise TypingError('Method shift(). Unsupported parameters. Given axis != 0')

        arr = numpy.empty(len(self._data), dtype=common_dtype)
        if periods > 0:
            arr[:periods] = fill_value
            arr[periods:] = self._data[:-periods]
        elif periods < 0:
            arr[periods:] = fill_value
            arr[:periods] = self._data[-periods:]
        else:
            arr[:] = self._data

        return pandas.Series(data=arr, index=self._index, name=self._name)

    return hpat_pandas_series_shift_impl


@sdc_overload_method(SeriesType, 'isin')
def hpat_pandas_series_isin(self, values):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.isin

    Limitations
    -----------
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_isin.py
       :language: python
       :lines: 27-
       :caption: Check whether values are contained in Series.
       :name: ex_series_isin

    .. command-output:: python ./series/series_isin.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`DataFrame.isin <pandas.DataFrame.isin>`
            Equivalent method on DataFrame.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.isin` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_isin*
    """

    _func_name = 'Method isin().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(values, (types.Set, types.List)):
        ty_checker.raise_exc(values, 'set or list', 'values')

    if isinstance(values.dtype, (types.UnicodeType, types.StringLiteral)):
        def hpat_pandas_series_isin_impl(self, values):
            # TODO: replace with below line when Numba supports np.isin in nopython mode
            # return pandas.Series (np.isin (self._data, values))

            values = str_list_to_array(list(values))
            values = build_set(values)
            data_len = len(self._data)
            result = numpy.empty(data_len, dtype=numpy.bool_)
            for i in prange(data_len):
                result[i] = self._data[i] in values

            return pandas.Series(data=result, index=self._index, name=self._name)
    else:
        def hpat_pandas_series_isin_impl(self, values):
            # TODO: replace with below line when Numba supports np.isin in nopython mode
            # return pandas.Series (np.isin (self._data, values))

            values = build_set(values)
            data_len = len(self._data)
            result = numpy.empty(data_len, dtype=numpy.bool_)
            for i in prange(data_len):
                result[i] = self._data[i] in values

            return pandas.Series(data=result, index=self._index, name=self._name)

    return hpat_pandas_series_isin_impl


@sdc_overload_method(SeriesType, 'append')
def hpat_pandas_series_append(self, to_append, ignore_index=False, verify_integrity=False):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.append

    Limitations
    -----------
    - Parameter ``verify_integrity`` is currently unsupported by Intel Scalable Dataframe Compiler
    - Parameter ``ignore_index`` is supported as literal value only
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_append.py
       :language: python
       :lines: 37-
       :caption: Concatenate two or more Series.
       :name: ex_series_append

    .. command-output:: python ./series/series_append.py
       :cwd: ../../../examples

    .. seealso::

        `pandas.absolute
        <https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.concat.html#pandas.concat>`_
            General function to concatenate DataFrame or Series objects.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.append` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_append*
    """

    _func_name = 'Method append().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    other_is_series = isinstance(to_append, SeriesType)
    if not (isinstance(to_append, SeriesType)
            or (isinstance(to_append, (types.UniTuple, types.List)) and isinstance(to_append.dtype, SeriesType))):
        ty_checker.raise_exc(to_append, 'series or list/tuple of series', 'to_append')

    # currently we will always raise this in the end, i.e. if no impl was found
    # TODO: find a way to stop compilation early and not proceed with unliteral step
    if not (isinstance(ignore_index, types.Literal) and isinstance(ignore_index, types.Boolean)
            or isinstance(ignore_index, types.Omitted)
            or ignore_index is False):
        ty_checker.raise_exc(ignore_index, 'literal Boolean constant', 'ignore_index')

    if not (verify_integrity is False or isinstance(verify_integrity, types.Omitted)):
        ty_checker.raise_exc(verify_integrity, 'bool', 'verify_integrity')

    # ignore_index value has to be known at compile time to select between implementations with different signatures
    ignore_index_is_false = (has_literal_value(ignore_index, False)
                             or has_python_value(ignore_index, False)
                             or isinstance(ignore_index, types.Omitted))
    to_append_is_series = isinstance(to_append, SeriesType)
    index_api_supported = not isinstance(self.index, sdc_old_index_types)

    if ignore_index_is_false:
        def hpat_pandas_series_append_impl(self, to_append, ignore_index=False, verify_integrity=False):
            if to_append_is_series == True:  # noqa
                new_data = common_functions.hpat_arrays_append(self._data, to_append._data)
                _self_index = self._index.values if index_api_supported == True else self._index  # noqa
                new_index = common_functions.hpat_arrays_append(_self_index, to_append._index)
            else:
                data_arrays_to_append = [series._data for series in to_append]
                index_arrays_to_append = [series._index for series in to_append]

                new_data = common_functions.hpat_arrays_append(self._data, data_arrays_to_append)
                _self_index = self._index.values if index_api_supported == True else self._index  # noqa
                new_index = common_functions.hpat_arrays_append(_self_index, index_arrays_to_append)

            return pandas.Series(new_data, new_index)

        return hpat_pandas_series_append_impl

    else:
        def hpat_pandas_series_append_ignore_index_impl(self, to_append, ignore_index=False, verify_integrity=False):

            if to_append_is_series == True:  # noqa
                new_data = common_functions.hpat_arrays_append(self._data, to_append._data)
            else:
                arrays_to_append = [series._data for series in to_append]
                new_data = common_functions.hpat_arrays_append(self._data, arrays_to_append)

            return pandas.Series(new_data, None)

        return hpat_pandas_series_append_ignore_index_impl


@sdc_overload_method(SeriesType, 'copy')
def hpat_pandas_series_copy(self, deep=True):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.copy

    Limitations
    -----------
    - When ``deep=False``, a new object will be created without copying the calling object’s data
    and with a copy of the calling object’s indices.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_copy.py
       :language: python
       :lines: 27-
       :caption: Make a copy of this object’s indices and data.
       :name: ex_series_copy

    .. command-output:: python ./series/series_copy.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.copy` implementation.

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series -k series_copy
    """

    ty_checker = TypeChecker('Method Series.copy().')
    ty_checker.check(self, SeriesType)

    if not isinstance(deep, (types.Omitted, types.Boolean)) and not deep:
        ty_checker.raise_exc(deep, 'boolean', 'deep')

    index_api_supported = not isinstance(self.index, sdc_old_index_types)

    def hpat_pandas_series_copy_impl(self, deep=True):
        new_series_data = numpy_like.copy(self._data) if deep else self._data

        if index_api_supported == False:  # noqa
            new_series_index = self._index.copy() if deep else self._index
        else:
            new_series_index = self._index.copy(deep=deep)
        return pandas.Series(new_series_data, new_series_index, name=self._name)

    return hpat_pandas_series_copy_impl


@sdc_overload_method(SeriesType, 'corr')
def hpat_pandas_series_corr(self, other, method='pearson', min_periods=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.corr

    Limitations
    -----------
    - Parameter ``method`` is supported only with default value 'pearson'

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_corr.py
       :language: python
       :lines: 27-
       :caption: Compute correlation with other Series, excluding missing values.
       :name: ex_series_corr

    .. command-output:: python ./series/series_corr.py
       :cwd: ../../../examples

    .. seealso::
        :ref:`Series.cov <pandas.Series.cov>`
            Compute covariance with Series, excluding missing values.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.corr` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_corr*
    """

    _func_name = 'Method corr().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    ty_checker.check(other, SeriesType)

    if not isinstance(self.data.dtype, types.Number):
        ty_checker.raise_exc(self.data, 'number', 'self.data')

    if not isinstance(other.data.dtype, types.Number):
        ty_checker.raise_exc(other.data, 'number', 'other.data')

    if not isinstance(min_periods, (int, types.Integer, types.Omitted, types.NoneType)) and min_periods is not None:
        ty_checker.raise_exc(min_periods, 'int64', 'min_periods')

    def hpat_pandas_series_corr_impl(self, other, method='pearson', min_periods=None):
        return numpy_like.corr(self, other, method, min_periods)

    return hpat_pandas_series_corr_impl


@sdc_overload_method(SeriesType, 'head')
def hpat_pandas_series_head(self, n=5):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.head

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_head.py
       :language: python
       :lines: 34-
       :caption: Getting the first n rows.
       :name: ex_series_head

    .. command-output:: python ./series/series_head.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`DataFrame.tail <pandas.DataFrame.tail>`

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.head` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_head*
    """

    _func_name = 'Method head().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(n, (types.Integer, types.Omitted, types.NoneType)) and n != 5:
        ty_checker.raise_exc(n, 'int', 'n')

    def hpat_pandas_series_head_index_impl(self, n=5):
        return pandas.Series(data=self._data[:n], index=self._index[:n], name=self._name)

    return hpat_pandas_series_head_index_impl


@sdc_overload_method(SeriesType, 'isnull')
def hpat_pandas_series_isnull(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.isnull

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_isnull.py
       :language: python
       :lines: 27-
       :caption: Detect missing values.
       :name: ex_series_isnull

    .. command-output:: python ./series/series_isnull.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.isnull` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_isnull*
    """

    _func_name = 'Method isnull().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if isinstance(self.data.dtype, (types.Number, types.Boolean, bool)):
        def hpat_pandas_series_isnull_impl(self):
            return pandas.Series(data=numpy_like.isnan(self._data), index=self._index, name=self._name)

        return hpat_pandas_series_isnull_impl

    if isinstance(self.data.dtype, types.UnicodeType):
        def hpat_pandas_series_isnull_impl(self):
            result = numpy.empty(len(self._data), numpy.bool_)
            byte_size = 8
            # iterate over bits in StringArrayType null_bitmap and fill array indicating if array's element are NaN
            for i in range(len(self._data)):
                bmap_idx = i // byte_size
                bit_idx = i % byte_size
                bmap = self._data.null_bitmap[bmap_idx]
                bit_value = (bmap >> bit_idx) & 1
                result[i] = bit_value == 0
            return pandas.Series(result, index=self._index, name=self._name)

        return hpat_pandas_series_isnull_impl


@sdc_overload_method(SeriesType, 'isna')
def hpat_pandas_series_isna(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.isna

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_isna.py
       :language: python
       :lines: 27-
       :caption: Detect missing values.
       :name: ex_series_isna

    .. command-output:: python ./series/series_isna.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.isnull <pandas.Series.isnull>`
            Alias of isna.

        :ref:`Series.notna <pandas.Series.notna>`
            Boolean inverse of isna.

        :ref:`Series.dropna <pandas.Series.dropna>`
            Omit axes labels with missing values.

        `pandas.absolute <https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.isna.html#pandas.isna>`_
            Top-level isna.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.isna` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_isna*
    """

    _func_name = 'Method isna().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if isinstance(self.data.dtype, (types.Number, types.Boolean, bool)):
        def hpat_pandas_series_isna_impl(self):
            return pandas.Series(data=numpy_like.isnan(self._data), index=self._index, name=self._name)

        return hpat_pandas_series_isna_impl

    if isinstance(self.data.dtype, types.UnicodeType):
        def hpat_pandas_series_isna_impl(self):
            result = numpy.empty(len(self._data), numpy.bool_)
            byte_size = 8
            # iterate over bits in StringArrayType null_bitmap and fill array indicating if array's element are NaN
            for i in range(len(self._data)):
                bmap_idx = i // byte_size
                bit_idx = i % byte_size
                bmap = self._data.null_bitmap[bmap_idx]
                bit_value = (bmap >> bit_idx) & 1
                result[i] = bit_value == 0
            return pandas.Series(result, index=self._index, name=self._name)

        return hpat_pandas_series_isna_impl


@sdc_overload_method(SeriesType, 'notna')
def hpat_pandas_series_notna(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.notna

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_notna.py
       :language: python
       :lines: 27-
       :caption: Detect existing (non-missing) values.
       :name: ex_series_notna

    .. command-output:: python ./series/series_notna.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.notnull <pandas.Series.notnull>`
            Alias of notna.

        :ref:`Series.isna <pandas.Series.isna>`
            Boolean inverse of notna.

        :ref:`Series.dropna <pandas.Series.dropna>`
            Omit axes labels with missing values.

        `pandas.absolute <https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.notna.html#pandas.notna>`_
            Top-level notna.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.notna` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_notna*
    """

    _func_name = 'Method notna().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if isinstance(self.data.dtype, (types.Number, types.Boolean, bool)):
        def hpat_pandas_series_notna_impl(self):
            return pandas.Series(numpy_like.notnan(self._data), index=self._index, name=self._name)

        return hpat_pandas_series_notna_impl

    if isinstance(self.data.dtype, types.UnicodeType):
        def hpat_pandas_series_notna_impl(self):
            result = self.isna()
            return pandas.Series(numpy.invert(result._data), index=self._index, name=self._name)

        return hpat_pandas_series_notna_impl


@sdc_overload_method(SeriesType, 'sum')
def hpat_pandas_series_sum(
    self,
    axis=None,
    skipna=None,
    level=None,
    numeric_only=None,
    min_count=0,
):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.sum

    Limitations
    -----------
    - Parameters ``axis``, ``level``, ``numeric_only`` and ``min_count`` \
        are currently unsupported by Intel Scalable Dataframe Compiler

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_sum.py
       :language: python
       :lines: 27-
       :caption: Return the sum of the values for the requested axis.
       :name: ex_series_sum

    .. command-output:: python ./series/series_sum.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.sum <pandas.Series.sum>`
            Return the sum.

        :ref:`Series.min <pandas.Series.min>`
            Return the minimum.

        :ref:`Series.max <pandas.Series.max>`
            Return the maximum.

        :ref:`Series.idxmin <pandas.Series.idxmin>`
            Return the index of the minimum.

        :ref:`Series.idxmax <pandas.Series.idxmax>`
            Return the index of the maximum.

        :ref:`DataFrame.sum <pandas.DataFrame.sum>`
            Return the sum over the requested axis.

        :ref:`DataFrame.min <pandas.DataFrame.min>`
            Return the minimum over the requested axis.

        :ref:`DataFrame.max <pandas.DataFrame.max>`
            Return the maximum over the requested axis.

        :ref:`DataFrame.idxmin <pandas.DataFrame.idxmin>`
            Return the index of the minimum over the requested axis.

        :ref:`DataFrame.idxmax <pandas.DataFrame.idxmax>`
            Return index of first occurrence of maximum over requested axis.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.sum` implementation.

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series -k series_sum
    """

    _func_name = 'Method sum().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not (isinstance(axis, (types.Integer, types.Omitted)) or axis is None):
        ty_checker.raise_exc(axis, 'int', 'axis')

    if not (isinstance(skipna, (types.Boolean, types.Omitted, types.NoneType)) or skipna is None):
        ty_checker.raise_exc(skipna, 'bool', 'skipna')

    if not (isinstance(level, (types.Integer, types.StringLiteral, types.Omitted, types.NoneType)) or level is None):
        ty_checker.raise_exc(level, 'int or str', 'level')

    if not (isinstance(numeric_only, (types.Boolean, types.Omitted)) or numeric_only is None):
        ty_checker.raise_exc(numeric_only, 'bool', 'numeric_only')

    if not (isinstance(min_count, (types.Integer, types.Omitted)) or min_count == 0):
        ty_checker.raise_exc(min_count, 'int', 'min_count')

    def hpat_pandas_series_sum_impl(
        self,
        axis=None,
        skipna=None,
        level=None,
        numeric_only=None,
        min_count=0,
    ):

        if skipna is None:
            _skipna = True
        else:
            _skipna = skipna

        if _skipna:
            return numpy_like.nansum(self._data)
        return numpy_like.sum(self._data)

    return hpat_pandas_series_sum_impl


@sdc_overload_method(SeriesType, 'take')
def hpat_pandas_series_take(self, indices, axis=0, is_copy=False):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.take

    Limitations
    -----------
    Parameter ``axis`` is supported only with default values ``0`` and ``'index'``.
    Parameter ``is_copy`` is supported only with default value ``False``.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_take.py
       :language: python
       :lines: 27-
       :caption: Return the elements in the given positional indices along an axis.
       :name: ex_series_take

    .. command-output:: python ./series/series_take.py
       :cwd: ../../../examples

    .. seealso::
        :ref:`DataFrame.loc <pandas.DataFrame.loc>`
            Select a subset of a DataFrame by labels.
        :ref:`DataFrame.iloc <pandas.DataFrame.iloc>`
            Select a subset of a DataFrame by positions.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************

    Pandas Series method :meth:`pandas.Series.take` implementation.

    .. only:: developer

        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_take_index_*
    """

    _func_name = 'Method take().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if (not isinstance(axis, (int, types.Integer, str, types.UnicodeType, types.StringLiteral, types.Omitted))
        and axis not in (0, 'index')):
        ty_checker.raise_exc(axis, 'integer or string', 'axis')

    if not isinstance(is_copy, (bool, types.Boolean, types.Omitted)) and is_copy is not False:
        ty_checker.raise_exc(is_copy, 'boolean', 'is_copy')

    if not isinstance(indices, (types.List, types.Array)):
        ty_checker.raise_exc(indices, 'array-like', 'indices')

    def hpat_pandas_series_take_impl(self, indices, axis=0, is_copy=False):
        local_data = [self._data[i] for i in indices]
        local_index = [self._index[i] for i in indices]

        return pandas.Series(local_data, local_index)

    return hpat_pandas_series_take_impl


@sdc_overload_method(SeriesType, 'idxmax')
def hpat_pandas_series_idxmax(self, axis=None, skipna=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.idxmax

    Limitations
    -----------
    Parameter ``axis`` is supported only with default value ``None``.
    Parameter ``skipna`` cannot be ``False`` with data of string type.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_idxmax.py
       :language: python
       :lines: 27-
       :caption: Getting the row label of the maximum value.
       :name: ex_series_idxmax

    .. command-output:: python ./series/series_idxmax.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.idxmin <pandas.Series.idxmin>`
            Return index label of the first occurrence of minimum of values.

        `numpy.absolute <https://docs.scipy.org/doc/numpy/reference/generated/numpy.argmax.html#numpy.argmax>`_
            Return indices of the maximum values along the given axis.

        :ref:`DataFrame.idxmax <pandas.DataFrame.idxmax>`
            Return index of first occurrence of maximum over requested axis.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.idxmax` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_idxmax*
    """

    _func_name = 'Method idxmax().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, types.Number):
        ty_checker.raise_exc(self.data.dtype, 'int, float', 'self.data.dtype')

    if not (isinstance(skipna, (types.Omitted, types.Boolean, bool)) or skipna is None):
        ty_checker.raise_exc(skipna, 'bool', 'skipna')

    if not (isinstance(axis, types.Omitted) or axis is None):
        ty_checker.raise_exc(axis, 'None', 'axis')

    positional_index = isinstance(self.index, PositionalIndexType)
    if isinstance(self.data, StringArrayType):
        def hpat_pandas_series_idxmax_str_impl(self, axis=None, skipna=None):
            if skipna is None:
                _skipna = True
            else:
                raise ValueError("Method idxmax(). Unsupported parameter 'skipna'=False with str data")

            result = numpy.argmax(self._data)
            if positional_index == True:  # noqa
                return result
            else:
                return self._index[int(result)]

        return hpat_pandas_series_idxmax_str_impl

    def hpat_pandas_series_idxmax_impl(self, axis=None, skipna=None):
        # return numpy.argmax(self._data)
        if skipna is None:
            _skipna = True
        else:
            _skipna = skipna

        if _skipna:
            result = numpy_like.nanargmax(self._data)
        else:
            result = numpy_like.argmax(self._data)

        if positional_index == True:  # noqa
            return result
        else:
            return self._index[int(result)]

        return numpy_like.argmax(self._data)

    return hpat_pandas_series_idxmax_impl


@sdc_overload_method(SeriesType, 'prod')
def hpat_pandas_series_prod(self, axis=None, skipna=None, level=None, numeric_only=None, min_count=0):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.prod

    Limitations
    -----------
    - Parameters ``axis``, ``level``, ``numeric_only`` and ``min_count`` \
        are currently unsupported by Intel Scalable Dataframe Compiler

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_prod.py
       :language: python
       :lines: 27-
       :caption: Return the product of the values.
       :name: ex_series_prod

    .. command-output:: python ./series/series_prod.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.prod` implementation.

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series -k series_prod
    """

    _func_name = 'Method prod().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, (types.Integer, types.Float)):
        ty_checker.raise_exc(self.data.dtype, 'numeric', 'self.data.dtype')

    if not (isinstance(axis, (types.Integer, types.Omitted)) or axis is None):
        ty_checker.raise_exc(axis, 'int', 'axis')

    if not (isinstance(skipna, (types.Omitted, types.Boolean, types.NoneType)) or skipna is None or skipna is True):
        ty_checker.raise_exc(skipna, 'bool', 'skipna')

    if not (isinstance(level, (types.Integer, types.StringLiteral, types.Omitted, types.NoneType)) or level is None):
        ty_checker.raise_exc(level, 'int or str', 'level')

    if not (isinstance(numeric_only, (types.Boolean, types.Omitted)) or numeric_only is None):
        ty_checker.raise_exc(numeric_only, 'bool', 'numeric_only')

    if not (isinstance(min_count, (types.Integer, types.Omitted)) or min_count == 0):
        ty_checker.raise_exc(min_count, 'int', 'min_count')

    def hpat_pandas_series_prod_impl(self, axis=None, skipna=None, level=None, numeric_only=None, min_count=0):
        if skipna is None:
            _skipna = True
        else:
            _skipna = skipna

        series_data = self._data  # FIXME_Numba#6960
        if _skipna:
            return numpy_like.nanprod(series_data)
        else:
            return numpy.prod(self._data)

    return hpat_pandas_series_prod_impl


@sdc_overload_method(SeriesType, 'quantile')
def hpat_pandas_series_quantile(self, q=0.5, interpolation='linear'):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.quantile

    Limitations
    -----------
    Parameter ``interpolation`` is currently unsupported.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_quantile.py
       :language: python
       :lines: 27-
       :caption: Computing quantile for the Series
       :name: ex_series_quantile

    .. command-output:: python ./series/series_quantile.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`core.window.Rolling.quantile <pandas.core.window.Rolling.quantile>`
            Calculate the rolling quantile.

        `numpy.percentile
        <https://docs.scipy.org/doc/numpy/reference/generated/numpy.percentile.html#numpy.percentile>`_
            Compute the q-th percentile of the data along the specified axis.


    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.quantile` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_quantile*
    """

    _func_name = 'Method quantile().'
    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(interpolation, types.Omitted) and interpolation != 'linear':
        ty_checker.raise_exc(interpolation, 'str', 'interpolation')

    if not isinstance(q, (int, float, list, types.Number, types.Omitted, types.List)):
        ty_checker.raise_exc(q, 'int, float, list', 'q')

    def hpat_pandas_series_quantile_impl(self, q=0.5, interpolation='linear'):

        return numpy.quantile(self._data, q)

    return hpat_pandas_series_quantile_impl


@sdc_overload_method(SeriesType, 'rename')
def hpat_pandas_series_rename(self, index=None, copy=True, inplace=False, level=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.rename

    Limitations
    -----------
    - Parameter ``level`` is currently unsupported by Intel Scalable Dataframe Compiler.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_rename.py
       :language: python
       :lines: 36-
       :caption: Alter Series index labels or name.
       :name: ex_series_rename

    .. command-output:: python ./series/series_rename.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.rename` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_rename
    """

    ty_checker = TypeChecker('Method rename().')
    ty_checker.check(self, SeriesType)

    if not isinstance(index, (types.Omitted, types.UnicodeType,
                              types.StringLiteral, str,
                              types.Integer, types.Boolean,
                              types.Hashable, types.Float,
                              types.NPDatetime, types.NPTimedelta,
                              types.Number)) and index is not None:
        ty_checker.raise_exc(index, 'string', 'index')

    if not isinstance(copy, (types.Omitted, types.Boolean, bool)):
        ty_checker.raise_exc(copy, 'boolean', 'copy')

    if not isinstance(inplace, (types.Omitted, types.Boolean, bool)):
        ty_checker.raise_exc(inplace, 'boolean', 'inplace')

    if not isinstance(level, (types.Omitted, types.UnicodeType,
                              types.StringLiteral, types.Integer)) and level is not None:
        ty_checker.raise_exc(level, 'Integer or string', 'level')

    def hpat_pandas_series_rename_impl(self, index=None, copy=True, inplace=False, level=None):
        if copy is True:
            series_data = self._data.copy()
            series_index = self._index.copy()
        else:
            series_data = self._data
            series_index = self._index

        return pandas.Series(data=series_data, index=series_index, name=index)

    return hpat_pandas_series_rename_impl


@sdc_overload_method(SeriesType, 'min')
def hpat_pandas_series_min(self, axis=None, skipna=None, level=None, numeric_only=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.min

    Limitations
    -----------
    Parameters ``level``, ``numeric_only`` and ``axis`` are currently unsupported by Intel Scalable Dataframe Compiler.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_min.py
       :language: python
       :lines: 27-
       :caption: Getting the minimum value of Series elements
       :name: ex_series_min

    .. command-output:: python ./series/series_min.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.sum <pandas.Series.sum>`
            Return the sum.

        :ref:`Series.min <pandas.Series.min>`
            Return the minimum.

        :ref:`Series.max <pandas.Series.max>`
            Return the maximum.

        :ref:`Series.idxmin <pandas.Series.idxmin>`
            Return the index of the minimum.

        :ref:`Series.idxmax <pandas.Series.idxmax>`
            Return the index of the maximum.

        :ref:`DataFrame.sum <pandas.DataFrame.sum>`
            Return the sum over the requested axis.

        :ref:`DataFrame.min <pandas.DataFrame.min>`
            Return the minimum over the requested axis.

        :ref:`DataFrame.max <pandas.DataFrame.max>`
            Return the maximum over the requested axis.

        :ref:`DataFrame.idxmin <pandas.DataFrame.idxmin>`
            Return the index of the minimum over the requested axis.

        :ref:`DataFrame.idxmax <pandas.DataFrame.idxmax>`
            Return the index of the maximum over the requested axis.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.min` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_min*
    """

    _func_name = 'Method min().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, (types.Integer, types.Float)):
        ty_checker.raise_exc(self.data.dtype, 'int, float', 'self.data.dtype')

    if not (isinstance(skipna, (types.Omitted, types.Boolean, types.NoneType)) or skipna is True or skipna is None):
        ty_checker.raise_exc(skipna, 'bool', 'skipna')

    if not isinstance(axis, types.Omitted) and axis is not None:
        ty_checker.raise_exc(axis, 'None', 'axis')

    if not isinstance(level, (types.Omitted, types.NoneType)) and level is not None:
        ty_checker.raise_exc(level, 'None', 'level')

    if not isinstance(numeric_only, types.Omitted) and numeric_only is not None:
        ty_checker.raise_exc(numeric_only, 'None', 'numeric_only')

    def hpat_pandas_series_min_impl(self, axis=None, skipna=None, level=None, numeric_only=None):
        if skipna is None:
            _skipna = True
        else:
            _skipna = skipna

        series_data = self._data  # FIXME_Numba#6960
        if _skipna:
            return numpy_like.nanmin(series_data)

        return self._data.min()

    return hpat_pandas_series_min_impl


@sdc_overload_method(SeriesType, 'max')
def hpat_pandas_series_max(self, axis=None, skipna=None, level=None, numeric_only=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.max

    Limitations
    -----------
    Parameters ``axis``, ``level`` and ``numeric_only`` are currently unsupported.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_max.py
       :language: python
       :lines: 27-
       :caption: Getting the maximum value of Series elements
       :name: ex_series_max

    .. command-output:: python ./series/series_max.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.sum <pandas.Series.sum>`
            Return the sum.
        :ref:`Series.min <pandas.Series.min>`
            Return the minimum.
        :ref:`Series.max <pandas.Series.max>`
            Return the maximum.
        :ref:`Series.idxmin <pandas.Series.idxmin>`
            Return the index of the minimum.
        :ref:`Series.idxmax <pandas.Series.idxmax>`
            Return the index of the maximum.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.max` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_max*
    """

    _func_name = 'Method max().'
    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, (types.Integer, types.Float)):
        ty_checker.raise_exc(self.data.dtype, 'int, float', 'self.data.dtype')

    if not (isinstance(skipna, (types.Omitted, types.Boolean, types.NoneType)) or skipna is True or skipna is None):
        ty_checker.raise_exc(skipna, 'bool', 'skipna')

    if not isinstance(axis, types.Omitted) and axis is not None:
        ty_checker.raise_exc(axis, 'None', 'axis')

    if not isinstance(level, (types.Omitted, types.NoneType)) and level is not None:
        ty_checker.raise_exc(level, 'None', 'level')

    if not isinstance(numeric_only, types.Omitted) and numeric_only is not None:
        ty_checker.raise_exc(numeric_only, 'None', 'numeric_only')

    def hpat_pandas_series_max_impl(self, axis=None, skipna=None, level=None, numeric_only=None):
        if skipna is None:
            _skipna = True
        else:
            _skipna = skipna

        series_data = self._data  # FIXME_Numba#6960
        if _skipna:
            return numpy_like.nanmax(series_data)

        return self._data.max()

    return hpat_pandas_series_max_impl


@sdc_overload_method(SeriesType, 'mean')
def hpat_pandas_series_mean(self, axis=None, skipna=None, level=None, numeric_only=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.mean

    Limitations
    -----------
    - Parameters ``axis``, ``level`` and ``numeric_only`` \
        are currently unsupported by Intel Scalable Dataframe Compiler.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_mean.py
       :language: python
       :lines: 27-
       :caption: Return the mean of the values.
       :name: ex_series_mean

    .. command-output:: python ./series/series_mean.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.mean` implementation.

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series -k series_mean
    """

    _func_name = 'Method mean().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, types.Number):
        ty_checker.raise_exc(self.data.dtype, 'numeric', 'self.data.dtype')

    if not isinstance(skipna, (types.Omitted, types.Boolean, types.NoneType)) and skipna is not None:
        ty_checker.raise_exc(skipna, 'bool', 'skipna')

    if not isinstance(axis, types.Omitted) and axis is not None:
        ty_checker.raise_exc(axis, 'None', 'axis')

    if not isinstance(level, (types.Omitted, types.NoneType)) and level is not None:
        ty_checker.raise_exc(level, 'None', 'level')

    if not isinstance(numeric_only, types.Omitted) and numeric_only is not None:
        ty_checker.raise_exc(numeric_only, 'None', 'numeric_only')

    def hpat_pandas_series_mean_impl(self, axis=None, skipna=None, level=None, numeric_only=None):
        if skipna is None:
            _skipna = True
        else:
            _skipna = skipna

        series_data = self._data  # FIXME_Numba#6960
        if _skipna:
            return numpy_like.nanmean(series_data)

        return self._data.mean()

    return hpat_pandas_series_mean_impl


@sdc_overload_method(SeriesType, 'idxmin')
def hpat_pandas_series_idxmin(self, axis=None, skipna=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.idxmin

    Limitations
    -----------
    - Parameter ``axis`` is supported only with default value ``None``.
    - Parameter ``skipna`` cannot be ``False`` with data of string type.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_idxmin.py
       :language: python
       :lines: 27-
       :caption: Getting the row label of the minimum value.
       :name: ex_series_idxmin

    .. command-output:: python ./series/series_idxmin.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.idxmax <pandas.Series.idxmax>`
            Return index label of the first occurrence of maximum of values.

        `numpy.argmin <https://docs.scipy.org/doc/numpy/reference/generated/numpy.argmin.html#numpy.argmin>`_
            Return indices of the minimum values along the given axis.

        :ref:`DataFrame.idxmin <pandas.DataFrame.idxmin>`
            Return index of first occurrence of minimum over requested axis.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.idxmin` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_idxmin*
    """

    _func_name = 'Method idxmin().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, types.Number):
        ty_checker.raise_exc(self.data.dtype, 'int, float', 'self.data.dtype')

    if not (isinstance(skipna, (types.Omitted, types.Boolean, bool)) or skipna is None):
        ty_checker.raise_exc(skipna, 'bool', 'skipna')

    if not (isinstance(axis, types.Omitted) or axis is None):
        ty_checker.raise_exc(axis, 'None', 'axis')

    positional_index = isinstance(self.index, PositionalIndexType)
    if isinstance(self.data, StringArrayType):
        def hpat_pandas_series_idxmin_str_impl(self, axis=None, skipna=None):
            if skipna is None:
                _skipna = True
            else:
                raise ValueError("Method idxmin(). Unsupported parameter 'skipna'=False with str data")

            result = numpy.argmin(self._data)
            if positional_index == True:  # noqa
                return result
            else:
                return self._index[int(result)]

        return hpat_pandas_series_idxmin_str_impl

    def hpat_pandas_series_idxmin_impl(self, axis=None, skipna=None):
        # return numpy.argmin(self._data)
        if skipna is None:
            _skipna = True
        else:
            _skipna = skipna

        if _skipna:
            result = numpy_like.nanargmin(self._data)
        else:
            result = numpy_like.argmin(self._data)

        if positional_index == True:  # noqa
            return result
        else:
            return self._index[int(result)]

        return numpy_like.argmin(self._data)

    return hpat_pandas_series_idxmin_impl


@sdc_overload_method(SeriesType, 'abs')
def hpat_pandas_series_abs(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.abs

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_abs.py
       :language: python
       :lines: 27-
       :caption: Getting the absolute value of each element in Series
       :name: ex_series_abs

    .. command-output:: python ./series/series_abs.py
       :cwd: ../../../examples

    .. seealso::

        `numpy.absolute <https://docs.scipy.org/doc/numpy/reference/generated/numpy.absolute.html>`_
            Calculate the absolute value element-wise.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.abs` implementation.

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_series_abs1
    """

    _func_name = 'Method abs().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.dtype, (types.Integer, types.Float)):
        raise TypingError(
            '{} The function only applies to elements that are all numeric. Given data type: {}'.format(_func_name,
                                                                                                        self.dtype))

    def hpat_pandas_series_abs_impl(self):
        return pandas.Series(numpy.abs(self._data))

    return hpat_pandas_series_abs_impl


@sdc_overload_method(SeriesType, 'unique')
def hpat_pandas_series_unique(self):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.unique

    Limitations
    -----------
    - Return values order is unspecified
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_unique.py
       :language: python
       :lines: 27-
       :caption: Getting unique values in Series
       :name: ex_series_unique

    .. command-output:: python ./series/series_unique.py
       :cwd: ../../../examples

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.unique` implementation.

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_unique_sorted
    """

    ty_checker = TypeChecker('Method unique().')
    ty_checker.check(self, SeriesType)

    if isinstance(self.data, StringArrayType):
        def hpat_pandas_series_unique_str_impl(self):
            '''
            Returns sorted unique elements of an array
            Note: Can't use Numpy due to StringArrayType has no ravel() for noPython mode.
            Also, NotImplementedError: unicode_type cannot be represented as a Numpy dtype

            Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_unique_str
            '''

            str_set = build_set(self._data)
            return to_array(str_set)

        return hpat_pandas_series_unique_str_impl

    def hpat_pandas_series_unique_impl(self):
        '''
        Returns sorted unique elements of an array

        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_unique
        '''

        return numpy.unique(self._data)

    return hpat_pandas_series_unique_impl


@sdc_overload_method(SeriesType, 'cumsum')
def hpat_pandas_series_cumsum(self, axis=None, skipna=True):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.cumsum

    Limitations
    -----------
    Parameter ``axis`` is supported only with default value ``None``.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_cumsum.py
       :language: python
       :lines: 27-
       :caption: Returns cumulative sum over Series.
       :name: ex_series_cumsum

    .. command-output:: python ./series/series_cumsum.py
       :cwd: ../../../examples

    .. seealso::
        :ref:`Series.sum <pandas.Series.sum>`
            Return the sum over Series.
        :ref:`Series.cummax <pandas.Series.cummax>`
            Return cumulative maximum over Series.
        :ref:`Series.cummin <pandas.Series.cummin>`
            Return cumulative minimum over Series.
        :ref:`Series.cumprod <pandas.Series.cumprod>`
            Return cumulative product over Series.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************

    Pandas Series method :meth:`pandas.Series.cumsum` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_cumsum*
    """

    _func_name = 'Method cumsum().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, types.Number):
        ty_checker.raise_exc(self.data.dtype, 'numeric', 'self.data.dtype')

    if not isinstance(axis, (types.Omitted, types.NoneType)) and axis is not None:
        ty_checker.raise_exc(axis, 'None', 'axis')

    def hpat_pandas_series_cumsum_impl(self, axis=None, skipna=True):
        if skipna:
            return pandas.Series(numpy_like.nancumsum(self._data, like_pandas=True))
        return pandas.Series(numpy_like.cumsum(self._data))

    return hpat_pandas_series_cumsum_impl


@sdc_overload_method(SeriesType, 'nunique')
def hpat_pandas_series_nunique(self, dropna=True):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.nunique

    Limitations
    -----------
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_nunique.py
       :language: python
       :lines: 27-
       :caption: Return number of unique elements in the object.
       :name: ex_series_nunique

    .. command-output:: python ./series/series_nunique.py
       :cwd: ../../../examples

    .. seealso::
        :ref:`DataFrame.nunique <pandas.DataFrame.nunique>`
            Method nunique for DataFrame.
        :ref:`Series.count <pandas.Series.count>`
            Count non-NA/null observations in the Series.
        :ref:`DatatFrame.count <pandas.DataFrame.count>`
            Count non-NA cells for each column

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.nunique` implementation.

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_series_nunique
    """

    _func_name = 'Method nunique().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if isinstance(self.data, StringArrayType):
        def hpat_pandas_series_nunique_str_impl(self, dropna=True):
            """
            It is better to merge with Numeric branch
            """
            data = self._data
            if dropna:
                nan_mask = self.isna()
                data = self._data[~nan_mask._data]
            unique_values = build_set(data)
            return len(unique_values)

        return hpat_pandas_series_nunique_str_impl

    def hpat_pandas_series_nunique_impl(self, dropna=True):
        """
        This function for Numeric data because NumPy dosn't support StringArrayType
        Algo looks a bit ambigous because, currently, set() can not be used with NumPy with Numba JIT
        """
        data_mask_for_nan = numpy.isnan(self._data)
        nan_exists = numpy.any(data_mask_for_nan)
        data_no_nan = self._data[~data_mask_for_nan]
        data_set = build_set(data_no_nan)
        if dropna or not nan_exists:
            return len(data_set)
        else:
            return len(data_set) + 1

    return hpat_pandas_series_nunique_impl


@sdc_overload_method(SeriesType, 'count')
def hpat_pandas_series_count(self, level=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.count

    Limitations
    -----------
    Parameter ``level`` is currently unsupported.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_count.py
       :language: python
       :lines: 27-
       :caption: Counting non-NaN values in Series
       :name: ex_series_count

    .. command-output:: python ./series/series_count.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.value_counts <pandas.Series.value_counts>`
            Return a Series containing counts of unique values.

        :ref:`Series.str.len <pandas.Series.str.len>`
            Count the length of each element in the Series.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.count` implementation.

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_series_count
    """

    _func_name = 'Method count().'
    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(level, (types.Omitted, types.NoneType)) and level is not None:
        ty_checker.raise_exc(level, 'None', 'level')

    if isinstance(self.data, StringArrayType):
        def hpat_pandas_series_count_str_impl(self, level=None):

            nan_mask = self.isna()
            return numpy.sum(nan_mask._data == 0)

        return hpat_pandas_series_count_str_impl

    if isinstance(self.data, types.Array) and isinstance(self.data.dtype, types.Integer):
        def hpat_pandas_series_count_int_impl(self, level=None):
            return len(self._data)
        return hpat_pandas_series_count_int_impl

    def hpat_pandas_series_count_impl(self, level=None):
        """
        Return number of non-NA/null observations in the object
        Returns number of unique elements in the object
        Test: python -m sdc.runtests sdc.tests.test_series.TestSeries.test_series_count
        """
        result = 0
        for i in prange(len(self._data)):
            if not numpy.isnan(self._data[i]):
                result = result + 1
        return result

    return hpat_pandas_series_count_impl


@sdc_overload_method(SeriesType, 'median')
def hpat_pandas_series_median(self, axis=None, skipna=None, level=None, numeric_only=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.median

    Limitations
    -----------
    - Parameters ``axis``, ``level`` and ``numeric_only`` are supported only with default value ``None``.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_median.py
       :language: python
       :lines: 27-
       :caption: Return the median of the values for the requested axis.
       :name: ex_series_median

    .. command-output:: python ./series/series_median.py
       :cwd: ../../../examples

    .. seealso::
        :ref:`DataFrame.median <pandas.DataFrame.median>`
            Return the median of the values for the columns.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.median` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_median1*
    """

    _func_name = 'Method median().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.dtype, types.Number):
        ty_checker.raise_exc(self.dtype, 'numeric', 'self.dtype')

    if not (isinstance(axis, (types.Integer, types.UnicodeType, types.Omitted)) or axis is None):
        ty_checker.raise_exc(axis, 'int or str', 'axis')

    if not (isinstance(skipna, (types.Boolean, types.Omitted, types.NoneType)) or skipna or skipna is None):
        ty_checker.raise_exc(skipna, 'bool', 'skipna')

    if not isinstance(axis, types.Omitted) and axis is not None:
        ty_checker.raise_exc(axis, 'None', 'axis')

    if not isinstance(level, (types.Omitted, types.NoneType)) and level is not None:
        ty_checker.raise_exc(level, 'None', 'level')

    if not isinstance(numeric_only, types.Omitted) and numeric_only is not None:
        ty_checker.raise_exc(numeric_only, 'None', 'numeric_only')

    def hpat_pandas_series_median_impl(self, axis=None, skipna=None, level=None, numeric_only=None):
        if skipna is None:
            _skipna = True
        else:
            _skipna = skipna

        if _skipna:
            return numpy.nanmedian(self._data)

        return numpy.median(self._data)

    return hpat_pandas_series_median_impl


@sdc_overload_method(SeriesType, 'argsort')
def hpat_pandas_series_argsort(self, axis=0, kind='quicksort', order=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.argsort

    Limitations
    -----------
    - Parameter ``axis`` is supported only with default value ``0``.
    - Parameter ``order`` is supported only with default value ``None``.
    - Parameter ``kind`` is supported only with values ``'mergesort'`` and ``'quicksort'``.
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_argsort.py
       :language: python
       :lines: 27-
       :caption: Override ndarray.argsort.
       :name: ex_series_argsort

    .. command-output:: python ./series/series_argsort.py
       :cwd: ../../../examples

    .. seealso::

        `numpy.ndarray.argsort
        <https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.argsort.html#numpy.ndarray.argsort>`_
            Return indices of the minimum values along the given axis.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.argsort` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_argsort*
    """

    _func_name = 'Method argsort().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, types.Number):
        ty_checker.raise_exc(self.data.dtype, 'int, float', 'self.data.dtype')

    if not (isinstance(axis, types.Omitted) or isinstance(axis, types.Integer) or axis == 0):
        ty_checker.raise_exc(axis, 'int64', 'axis')

    if not isinstance(kind, (types.Omitted, str, types.UnicodeType, types.StringLiteral)):
        ty_checker.raise_exc(kind, 'quicksort', 'kind')

    if not isinstance(order, (str, types.UnicodeType, types.StringLiteral, types.Omitted, types.NoneType, types.List))\
            and order is not None:
        ty_checker.raise_exc(order, 'None', 'order')

    if not isinstance(self.index, PositionalIndexType):
        def hpat_pandas_series_argsort_idx_impl(self, axis=0, kind='quicksort', order=None):
            series_data = self._data  # FIXME_Numba#6960
            if kind != 'quicksort' and kind != 'mergesort':
                raise ValueError("Method argsort(). Unsupported parameter. Given 'kind' != 'quicksort' or 'mergesort'")
            if kind == 'mergesort':
                #It is impossible to use numpy.argsort(self._data, kind=kind) since numba gives typing error
                sort = numpy_like.argsort(series_data, kind='mergesort')
            else:
                sort = numpy_like.argsort(series_data)
            na = self.isna().sum()
            result = numpy.empty(len(series_data), dtype=numpy.int64)
            na_data_arr = sdc.hiframes.api.get_nan_mask(series_data)
            if kind == 'mergesort':
                sort_nona = numpy_like.argsort(series_data[~na_data_arr], kind='mergesort')
            else:
                sort_nona = numpy_like.argsort(series_data[~na_data_arr])
            q = 0
            for id, i in enumerate(sort):
                if id in set(sort[len(series_data) - na:]):
                    q += 1
                else:
                    result[id] = sort_nona[id - q]
            for i in sort[len(series_data) - na:]:
                result[i] = -1

            return pandas.Series(result, self._index)

        return hpat_pandas_series_argsort_idx_impl

    def hpat_pandas_series_argsort_noidx_impl(self, axis=0, kind='quicksort', order=None):
        series_data = self._data  # FIXME_Numba#6960
        if kind != 'quicksort' and kind != 'mergesort':
            raise ValueError("Method argsort(). Unsupported parameter. Given 'kind' != 'quicksort' or 'mergesort'")
        if kind == 'mergesort':
            sort = numpy_like.argsort(series_data, kind='mergesort')
        else:
            sort = numpy_like.argsort(series_data)
        na = self.isna().sum()
        result = numpy.empty(len(series_data), dtype=numpy.int64)
        na_data_arr = sdc.hiframes.api.get_nan_mask(series_data)
        if kind == 'mergesort':
            sort_nona = numpy_like.argsort(series_data[~na_data_arr], kind='mergesort')
        else:
            sort_nona = numpy_like.argsort(series_data[~na_data_arr])
        q = 0
        for id, i in enumerate(sort):
            if id in set(sort[len(series_data) - na:]):
                q += 1
            else:
                result[id] = sort_nona[id - q]
        for i in sort[len(series_data) - na:]:
            result[i] = -1

        return pandas.Series(result)

    return hpat_pandas_series_argsort_noidx_impl


@sdc_overload_method(SeriesType, 'sort_values', parallel=False)
def hpat_pandas_series_sort_values(self, axis=0, ascending=True, inplace=False, kind='quicksort', na_position='last'):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.sort_values

    Limitations
    -----------
    - Parameter ``inplace`` is supported only with default value ``False``.
    - Parameter ``axis`` is currently unsupported by Intel Scalable Dataframe Compiler.
    - Parameter ``kind`` is supported only with values ``'mergesort'`` and ``'quicksort'``.
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_sort_values.py
       :language: python
       :lines: 36-
       :caption: Sort by the values.
       :name: ex_series_sort_values

    .. command-output:: python ./series/series_sort_values.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.sort_index <pandas.Series.sort_index>`
            Sort by the Series indices.

        :ref:`DataFrame.sort_values <pandas.DataFrame.sort_values>`
            Sort DataFrame by the values along either axis.

        :ref:`DataFrame.sort_index <pandas.DataFrame.sort_index>`
            Sort DataFrame by indices.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.sort_values` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_sort_values*
    """

    _func_name = 'Method sort_values().'

    ty_checker = TypeChecker('Method sort_values().')
    ty_checker.check(self, SeriesType)

    axis_supported_types = (int, types.Omitted, types.Integer, types.StringLiteral, types.UnicodeType)
    if not isinstance(axis, axis_supported_types):
        ty_checker.raise_exc(axis, 'integer or string', 'axis')

    ascending_supported_types = (bool, types.Omitted, types.Boolean)
    if not isinstance(ascending, ascending_supported_types):
        ty_checker.raise_exc(ascending, 'boolean', 'ascending')

    kind_supported_types = (str, types.Omitted, types.NoneType, types.StringLiteral, types.UnicodeType)
    if not isinstance(kind, kind_supported_types):
        ty_checker.raise_exc(kind, 'string', 'kind')
    kind_is_none_or_default = isinstance(kind, (str, types.Omitted, types.NoneType))

    na_position_supported_types = (str, types.Omitted, types.StringLiteral, types.UnicodeType)
    if not isinstance(na_position, na_position_supported_types):
        ty_checker.raise_exc(na_position, 'string', 'na_position')

    if not (inplace is False or isinstance(inplace, types.Omitted)):
        raise TypingError('{} Unsupported parameters. Given inplace: {}'.format(_func_name, inplace))

    def _sdc_pandas_series_sort_values_impl(
            self, axis=0, ascending=True, inplace=False, kind='quicksort', na_position='last'):

        common_functions._sdc_pandas_series_check_axis(axis)

        if not (kind_is_none_or_default or kind in ('quicksort', 'mergesort')):
            raise ValueError("Method sort_values(). Unsupported parameter. Given kind != 'quicksort', 'mergesort'")

        if na_position not in ('last', 'first'):
            raise ValueError("Method sort_values(). Unsupported parameter. Given na_position != 'last', 'first'")

        data_nan_mask = sdc.hiframes.api.get_nan_mask(self._data)
        good = ~data_nan_mask

        if kind_is_none_or_default == True:  # noqa
            argsort_res = sdc_arrays_argsort(self._data[good], kind='quicksort', ascending=ascending)
        else:
            argsort_res = sdc_arrays_argsort(self._data[good], kind=kind, ascending=ascending)

        idx = numpy.arange(len(self), dtype=numpy.int32)
        sorted_index = numpy.empty(len(self), dtype=numpy.int32)
        if na_position == "last":
            nans_start, nans_stop = good.sum(), len(self)
            sorted_index[:nans_start] = idx[good][argsort_res]
            sorted_index[nans_start: nans_stop] = idx[data_nan_mask]
        elif na_position == "first":
            nans_start, nans_stop = 0, data_nan_mask.sum()
            sorted_index[nans_stop:] = idx[good][argsort_res]
            sorted_index[:nans_stop] = idx[data_nan_mask]

        result_data = self._data[sorted_index]
        result_index = self.index[sorted_index]

        return pandas.Series(data=result_data, index=result_index, name=self._name)

    return _sdc_pandas_series_sort_values_impl


@sdc_overload_method(SeriesType, 'dropna')
def hpat_pandas_series_dropna(self, axis=0, inplace=False):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.dropna

    Limitations
    -----------
    - Parameters ``inplace`` and ``axis`` are currently unsupported by Intel Scalable Dataframe Compiler.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_dropna.py
       :language: python
       :lines: 34-
       :caption: Return a new Series with missing values removed.
       :name: ex_series_dropna

    .. command-output:: python ./series/series_dropna.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.isna <pandas.Series.isna>`
            Indicate missing values.

        :ref:`Series.notna <pandas.Series.notna>`
            Indicate existing (non-missing) values.

        :ref:`Series.fillna <pandas.Series.fillna>`
            Replace missing values.

        :ref:`DataFrame.dropna <pandas.DataFrame.dropna>`
            Drop rows or columns which contain NA values.

        `pandas.Index.dropna
        <https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Index.dropna.html#pandas.Index.dropna>`_
            Return Index without NA/NaN values

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.dropna` implementation.

    .. only:: developer
       Tests: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_dropna*
    """

    _func_name = 'Method dropna().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not (isinstance(axis, (types.Integer, types.StringLiteral, types.UnicodeType, types.Omitted)) or axis == 0):
        ty_checker.raise_exc(axis, 'int or str', 'axis')

    if not (inplace is False or isinstance(inplace, types.Omitted)):
        ty_checker.raise_exc(inplace, 'bool', 'inplace')

    # if both data and index are numeric (i.e. types.Array) dispatch to numpy_like.dropna impl
    if (isinstance(self.dtype, types.Number) and isinstance(self.index.dtype, types.Number)):
        def hpat_pandas_series_dropna_impl(self, axis=0, inplace=False):
            return numpy_like.dropna(self._data, self._index, self._name)

        return hpat_pandas_series_dropna_impl

    else:
        def hpat_pandas_series_dropna_str_impl(self, axis=0, inplace=False):
            # TO-DO: verify these operations are fused
            na_data_arr = sdc.hiframes.api.get_nan_mask(self._data)
            data = self._data[~na_data_arr]
            index = self._index[~na_data_arr]
            return pandas.Series(data, index, self._name)

        return hpat_pandas_series_dropna_str_impl


@sdc_overload_method(SeriesType, 'fillna')
def hpat_pandas_series_fillna(self, value=None, method=None, axis=None, inplace=False, limit=None, downcast=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.fillna

    Limitations
    -----------
    - Parameters ``method``, ``limit`` and ``downcast`` are currently unsupported
    by Intel Scalable Dataframe Compiler.
    - Parameter ``inplace`` is supported with literal value only.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_fillna.py
       :language: python
       :lines: 35-
       :caption: Fill NA/NaN values using the specified method.
       :name: ex_series_fillna

    .. command-output:: python ./series/series_fillna.py
       :cwd: ../../../examples

    .. seealso::

        `pandas.interpolate
        <https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.interpolate.html#pandas.Series.interpolate>`_
            Fill NaN values using interpolation.

        `pandas.reindex
        <https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.reindex.html#pandas.Series.reindex>`_
            Conform object to new index.

        `pandas.asfreq
        <https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.asfreq.html#pandas.Series.asfreq>`_
            Convert TimeSeries to specified frequency.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.fillna` implementation.

    .. only:: developer
       Tests: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_fillna*
    """

    _func_name = 'Method fillna().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not (isinstance(axis, (types.Integer, types.StringLiteral, types.UnicodeType, types.Omitted)) or axis is None):
        ty_checker.raise_exc(axis, 'int or str', 'axis')

    if not (isinstance(inplace, types.Literal) and isinstance(inplace, types.Boolean)
            or isinstance(inplace, types.Omitted)
            or inplace is False):
        ty_checker.raise_exc(inplace, 'bool', 'inplace')

    if not isinstance(method, (types.Omitted, types.NoneType)) and method is not None:
        ty_checker.raise_exc(method, 'None', 'method')

    if not isinstance(limit, (types.Omitted, types.NoneType)) and limit is not None:
        ty_checker.raise_exc(limit, 'None', 'limit')

    if not isinstance(downcast, (types.Omitted, types.NoneType)) and downcast is not None:
        ty_checker.raise_exc(downcast, 'None', 'downcast')

    # inplace value has to be known at compile time to select between implementations with different signatures
    if ((isinstance(inplace, types.Literal) and inplace.literal_value == True)
        or (isinstance(inplace, bool) and inplace == True)):
        # do operation inplace, fill the NA/NaNs in the same array and return None
        if isinstance(self.dtype, types.UnicodeType):
            # TODO: StringArrayType cannot resize inplace, and assigning a copy back to self._data is not possible now
            raise TypingError('{} Not implemented when Series dtype is {} and\
                 inplace={}'.format(_func_name, self.dtype, inplace))

        else:
            def hpat_pandas_series_fillna_impl(self, value=None, method=None, axis=None, inplace=False,
                                               limit=None, downcast=None):
                return numpy_like.fillna(self._data, inplace=inplace, value=value)

            return hpat_pandas_series_fillna_impl

    else:
        # non inplace implementations, copy array, fill the NA/NaN and return a new Series
        if isinstance(self.dtype, types.UnicodeType):
            def hpat_pandas_series_str_fillna_impl(self, value=None, method=None, axis=None,
                                                   inplace=False, limit=None, downcast=None):
                return pandas.Series(data=numpy_like.fillna(self._data, inplace=inplace, value=value),
                                     index=self._index,
                                     name=self._name)

            return hpat_pandas_series_str_fillna_impl

        elif isinstance(self.dtype, (types.Integer, types.Boolean)):
            def hpat_pandas_series_no_nan_fillna_impl(self, value=None, method=None, axis=None, inplace=False, limit=None, downcast=None):
                return pandas.Series(data=numpy_like.fillna(self._data, inplace=inplace, value=value),
                                     index=self._index,
                                     name=self._name)

            return hpat_pandas_series_no_nan_fillna_impl

        else:
            def hpat_pandas_series_fillna_impl(self, value=None, method=None, axis=None, inplace=False, limit=None, downcast=None):
                filled_data = numpy_like.fillna(self._data, inplace=inplace, value=value)
                return pandas.Series(data=filled_data,
                                     index=self._index,
                                     name=self._name)

            return hpat_pandas_series_fillna_impl


@sdc_overload_method(SeriesType, 'cov')
def hpat_pandas_series_cov(self, other, min_periods=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.cov

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_cov.py
       :language: python
       :lines: 27-
       :caption: Compute covariance with Series, excluding missing values.
       :name: ex_series_cov

    .. command-output:: python ./series/series_cov.py
       :cwd: ../../../examples

    .. seealso::
        :ref:`Series.corr <pandas.Series.corr>`
            Compute correlation with other Series, excluding missing values.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.cov` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_cov*
    """

    ty_checker = TypeChecker('Method cov().')
    ty_checker.check(self, SeriesType)

    ty_checker.check(other, SeriesType)

    if not isinstance(self.data.dtype, types.Number):
        ty_checker.raise_exc(self.data.dtype, 'number', 'self.data')

    if not isinstance(other.data.dtype, types.Number):
        ty_checker.raise_exc(other.data.dtype, 'number', 'other.data')

    if not isinstance(min_periods, (types.Integer, types.Omitted, types.NoneType)) and min_periods is not None:
        ty_checker.raise_exc(min_periods, 'int64', 'min_periods')

    def hpat_pandas_series_cov_impl(self, other, min_periods=None):

        if min_periods is None:
            min_periods = 2

        if min_periods < 2:
            min_periods = 2

        min_len = min(len(self._data), len(other._data))

        if min_len == 0:
            return numpy.nan

        other_sum = 0.
        self_sum = 0.
        self_other_sum = 0.
        total_count = 0
        for i in prange(min_len):
            s = self._data[i]
            o = other._data[i]
            if not (numpy.isnan(s) or numpy.isnan(o)):
                self_sum += s
                other_sum += o
                self_other_sum += s*o
                total_count += 1

        if total_count < min_periods:
            return numpy.nan

        return (self_other_sum - self_sum*other_sum/total_count)/(total_count - 1)

    return hpat_pandas_series_cov_impl


@sdc_overload_method(SeriesType, 'pct_change', parallel=False)
def hpat_pandas_series_pct_change(self, periods=1, fill_method='pad', limit=None, freq=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.pct_change

    Limitations
    -----------
    - Parameters limit, freq are currently unsupported by Intel Scalable Dataframe Compiler
    - This function may reveal slower performance than Pandas* on user system. Users should exercise a tradeoff
    between staying in JIT-region with that function or going back to interpreter mode.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_pct_change.py
       :language: python
       :lines: 36-
       :caption: Percentage change between the current and a prior element.
       :name: ex_series_pct_change

    .. command-output:: python ./series/series_pct_change.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.diff <pandas.Series.diff>`
            Compute the difference of two elements in a Series.

        :ref:`DataFrame.diff <pandas.DataFrame.diff>`
            Compute the difference of two elements in a DataFrame.

        :ref:`Series.shift <pandas.Series.shift>`
            Shift the index by some number of periods.

        :ref:`DataFrame.shift <pandas.DataFrame.shift>`
            Shift the index by some number of periods.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.pct_change` implementation.

    .. only:: developer
        Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_pct_change
    """

    ty_checker = TypeChecker('Method pct_change().')
    ty_checker.check(self, SeriesType)

    if not isinstance(self.data.dtype, types.Number):
        ty_checker.raise_exc(self.data.dtype, 'number', 'self.data')

    if not isinstance(periods, (types.Integer, types.Omitted)):
        ty_checker.raise_exc(periods, 'int64', 'periods')

    if not isinstance(fill_method, (str, types.UnicodeType, types.StringLiteral, types.NoneType, types.Omitted)):
        ty_checker.raise_exc(fill_method, 'string', 'fill_method')

    if not isinstance(limit, (types.Omitted, types.NoneType)):
        ty_checker.raise_exc(limit, 'None', 'limit')

    if not isinstance(freq, (types.Omitted, types.NoneType)):
        ty_checker.raise_exc(freq, 'None', 'freq')

    def hpat_pandas_series_pct_change_impl(self, periods=1, fill_method='pad', limit=None, freq=None):
        if not (fill_method is None or fill_method in ['pad', 'ffill', 'backfill', 'bfill']):
            raise ValueError(
                "Method pct_change(). Unsupported parameter. The function uses fill_method pad (ffill) or backfill (bfill) or None.")
        local_series = self.copy()
        if fill_method is not None:
            # replacement method fillna for given method
            # =========================================
            # Example:
            # s = [1.1, 0.3, np.nan, 1, np.inf, 0, 1.1, np.nan, 2.2, np.inf, 2, 2]
            # result = [1.1, 0.3, 0.3, 1, inf, 0, 1.1, 1.1, 2.2, inf, 2, 2]
            # ==========================================
            for i in range(len(local_series._data)):
                # check each element on numpy.nan
                if numpy.isnan(local_series._data[i]):
                    if fill_method in ['pad', 'ffill']:
                        # if it first element is nan, element will be is nan
                        # if it not first element, element will be is nearest is not nan element
                        # take a step back while will not find is not nan element
                        # if before the first element you did not find one, the element will be equal nan
                        if i == 0:
                            local_series._data[i] = numpy.nan
                        else:
                            k = 1
                            while numpy.isnan(local_series._data[i - k]):
                                if i - k == 0:
                                    local_series._data[i] = numpy.nan
                                    break
                                k += 1
                            local_series._data[i] = local_series._data[i - k]
                    elif fill_method in ['backfill', 'bfill']:
                        # if it last element is nan, element will be is nan
                        # if it not last element, element will be is nearest is not nan element
                        # take a step front while will not find is not nan element
                        # if before the last element you did not find one, the element will be equal nan
                        if i == len(local_series._data)-1:
                            local_series._data[i] = numpy.nan
                        else:
                            k = 1
                            while numpy.isnan(local_series._data[i + k]):
                                if i + k == len(local_series._data) - 1:
                                    local_series._data[i] = numpy.nan
                                    break
                                k += 1
                            local_series._data[i] = local_series._data[i + k]
        rshift = local_series.shift(periods=periods, freq=freq)
        rdiv = local_series.div(rshift)
        result = rdiv._data - 1
        return pandas.Series(result)

    return hpat_pandas_series_pct_change_impl


@sdc_overload_method(SeriesType, 'describe')
def hpat_pandas_series_describe(self, percentiles=None, include=None, exclude=None):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.describe

    Limitations
    -----------
    - Parameters ``include`` and ``exclude`` are currently unsupported by Intel Scalable Dataframe Compiler.
    - For string Series resulting values are returned as strings.

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_describe.py
       :language: python
       :lines: 39-
       :caption: Generate descriptive statistics.
       :name: ex_series_describe

    .. command-output:: python ./series/series_describe.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`DataFrame.count <pandas.DataFrame.count>`
            Count number of non-NA/null observations.

        :ref:`DataFrame.max <pandas.DataFrame.max>`
            Maximum of the values in the object.

        :ref:`DataFrame.min <pandas.DataFrame.min>`
            Minimum of the values in the object.

        :ref:`DataFrame.mean <pandas.DataFrame.mean>`
            Mean of the values.

        :ref:`DataFrame.std <pandas.DataFrame.std>`
            Standard deviation of the observations.

        :ref:`DataFrame.select_dtypes <pandas.DataFrame.select_dtypes>`
            Subset of a DataFrame including/excluding columns based on their dtype.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.describe` implementation.

    .. only:: developer

       Tests: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_describe*
    """

    _func_name = 'Method describe().'
    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not (isinstance(percentiles, (types.List, types.Array, types.UniTuple))
            and isinstance(percentiles.dtype, types.Number)
            or isinstance(percentiles, (types.Omitted, types.NoneType))
            or percentiles is None):
        ty_checker.raise_exc(percentiles, 'list-like', 'percentiles')

    if not (isinstance(include, (types.Omitted, types.NoneType)) or include is None):
        raise TypingError('{} Unsupported parameters. Given include: {}'.format(_func_name, include))

    if not (isinstance(exclude, (types.Omitted, types.NoneType)) or exclude is None):
        raise TypingError('{} Unsupported parameters. Given exclude: {}'.format(_func_name, exclude))

    is_percentiles_none = percentiles is None or isinstance(percentiles, (types.Omitted, types.NoneType))

    if isinstance(self.dtype, types.Number):
        def hpat_pandas_series_describe_numeric_impl(self, percentiles=None, include=None, exclude=None):

            if is_percentiles_none == False:  # noqa
                percentiles_list = list(percentiles)
                median_in_percentiles = 0.5 in percentiles_list
                if not median_in_percentiles:
                    percentiles_list.append(0.5)
                sorted_percentiles = sorted(percentiles_list)

                # check percentiles have correct values:
                arr = numpy.asarray(sorted_percentiles)
                if len(numpy.unique(arr)) != len(arr):
                    raise ValueError("percentiles cannot contain duplicates")
                if numpy.any(arr[(arr < 0) * (arr > 1)]):
                    raise ValueError("percentiles should all be in the interval [0, 1].")

                # TODO: support proper rounding of percentiles like in pandas.io.formats.format.format_percentiles
                # requires numpy.round(precision), numpy.isclose to be supported by Numba
                percentiles_indexes = common_functions._sdc_pandas_format_percentiles(arr)
            else:
                sorted_percentiles = [0.25, 0.5, 0.75]
                percentiles_indexes = ['25%', '50%', '75%']

            index_strings = ['count', 'mean', 'std', 'min']
            index_strings.extend(percentiles_indexes)
            index_strings.append('max')

            values = []
            values.append(numpy.float64(self.count()))
            values.append(self.mean())
            values.append(self.std())
            values.append(self.min())
            for p in sorted_percentiles:
                values.append(self.quantile(p))
            values.append(self.max())

            return pandas.Series(values, index_strings)

        return hpat_pandas_series_describe_numeric_impl

    elif isinstance(self.dtype, types.UnicodeType):
        def hpat_pandas_series_describe_string_impl(self, percentiles=None, include=None, exclude=None):

            objcounts = self.value_counts()
            index_strings = ['count', 'unique', 'top', 'freq']

            # use list of strings for the output series, since Numba doesn't support np.arrays with object dtype
            values = []
            values.append(str(self.count()))
            values.append(str(len(self.unique())))
            values.append(str(objcounts.index[0]))
            values.append(str(objcounts.iloc[0]))

            return pandas.Series(values, index_strings)

        return hpat_pandas_series_describe_string_impl

    elif isinstance(self.dtype, (types.NPDatetime, types.NPTimedelta)):
        # TODO: provide specialization for (types.NPDatetime, types.NPTimedelta)
        # needs dropna for date-time series, conversion to int and tz_convert to be implemented
        return None

    return None


@sdc_overload(operator.add, parallel=False)
def sdc_pandas_str_series_operator_add(self, other):
    """
    Additional overload of operator.add for Series of strings.
    For generic overload see - autogenerated one in sdc_autogenerated.py
    """

    _func_name = 'Operator add().'

    ty_checker = TypeChecker('Operator add().')
    self_is_series, other_is_series = isinstance(self, SeriesType), isinstance(other, SeriesType)
    if not (self_is_series or other_is_series):
        return None

    # this overload is for string series only (so check that at least one is series of strings)
    self_is_string_series = self_is_series and isinstance(self.dtype, types.UnicodeType)
    other_is_string_series = other_is_series and isinstance(other.dtype, types.UnicodeType)
    if not (self_is_string_series or other_is_string_series):
        return None

    if not isinstance(self, (SeriesType, types.Number, types.UnicodeType)):
        ty_checker.raise_exc(self, 'pandas.series or string', 'self')

    if not isinstance(other, (SeriesType, types.Number, types.UnicodeType)):
        ty_checker.raise_exc(other, 'pandas.series or string', 'other')

    operands_are_series = self_is_series and other_is_series
    if operands_are_series:
        series_indexes_comparable = check_types_comparable(self.index, other.index)
        if not series_indexes_comparable:
            raise TypingError('{} Not implemented for series with not-comparable indexes. \
            Given: self.index={}, other.index={}'.format(_func_name, self.index, other.index))

    series_data_comparable = check_types_comparable(self, other)
    if not series_data_comparable:
        raise TypingError('{} Not supported for not-comparable operands. \
        Given: self={}, other={}'.format(_func_name, self, other))

    if not operands_are_series:
        def _series_operator_add_scalar_impl(self, other):
            if self_is_series == True:  # noqa
                result_data = self._data + other
                return pandas.Series(result_data, index=self._index, name=self._name)
            else:
                result_data = self + other._data
                return pandas.Series(result_data, index=other._index, name=other._name)

        return _series_operator_add_scalar_impl
    else:   # both operands are string series

        # TO-DO: None indexes branch is dead code, remove?
        if (isinstance(self.index, PositionalIndexType) and isinstance(other.index, PositionalIndexType)):
            def _series_operator_add_none_indexes_impl(self, other):

                if (len(self._data) == len(other._data)):
                    result_data = self._data + other._data
                    return pandas.Series(result_data)
                else:
                    left_size, right_size = len(self._data), len(other._data)
                    min_data_size = min(left_size, right_size)
                    max_data_size = max(left_size, right_size)

                    result_data_as_list = []
                    result_nan_mask = numpy.zeros(max_data_size, dtype=numpy.bool_)
                    result_nan_mask[min_data_size:] = True
                    for i in numpy.arange(min_data_size):
                        if str_arr_is_na(self._data, i) or str_arr_is_na(other._data, i):
                            result_nan_mask[i] = True
                            result_data_as_list.append('')
                        else:
                            result_data_as_list.append(self._data[i] + other._data[i])
                    result_data_as_list.extend([''] * (max_data_size - min_data_size))
                    result_data = create_str_arr_from_list(result_data_as_list)
                    str_arr_set_na_by_mask(result_data, result_nan_mask)

                    return pandas.Series(result_data, self._index)

            return _series_operator_add_none_indexes_impl
        else:

            index_api_supported = not (isinstance(self.index, sdc_old_index_types)
                                       or isinstance(other.index, sdc_old_index_types))

            def _series_operator_add_str_impl(self, other):
                left_index, right_index = self._index, other._index
                if index_api_supported == True:  # noqa
                    indexes_join_res = left_index.join(right_index, 'outer', return_indexers=True)
                else:
                    indexes_join_res = sdc_indexes_join_outer(left_index, right_index)

                # FIXME_Numba#XXXX: remove sdc_fix_indexes_join call at all when issue is fixed
                joined_index, left_indexer, right_indexer = sdc_fix_indexes_join(*indexes_join_res)
                result_size = len(joined_index)
                result_nan_mask = numpy.zeros(result_size, dtype=numpy.bool_)
                result_data_as_list = []
                for i in numpy.arange(result_size):
                    if (left_indexer[i] == -1
                            or right_indexer[i] == -1
                            or str_arr_is_na(self._data, left_indexer[i])
                            or str_arr_is_na(other._data, right_indexer[i])):
                        result_nan_mask[i] = True
                        result_data_as_list.append('')
                    else:
                        result_data_as_list.append(self._data[left_indexer[i]] + other._data[right_indexer[i]])

                result_data = create_str_arr_from_list(result_data_as_list)
                str_arr_set_na_by_mask(result_data, result_nan_mask)

                return pandas.Series(result_data, joined_index)

            return _series_operator_add_str_impl

    return None


@sdc_overload(operator.mul, parallel=False)
def sdc_pandas_str_series_operator_mul(self, other):
    """
    Additional overload of operator.add for Series of strings.
    For generic overload see - autogenerated one in sdc_autogenerated.py
    """

    _func_name = 'Operator mul().'

    ty_checker = TypeChecker(_func_name)
    self_is_series, other_is_series = isinstance(self, SeriesType), isinstance(other, SeriesType)
    if not (self_is_series or other_is_series):
        return None

    # this overload is for string series only (but another might well be series of integers)
    self_is_string_series = self_is_series and isinstance(self.dtype, types.UnicodeType)
    other_is_string_series = other_is_series and isinstance(other.dtype, types.UnicodeType)
    if not (self_is_string_series or other_is_string_series):
        return None

    if not isinstance(self, (SeriesType, types.Number, types.UnicodeType)):
        ty_checker.raise_exc(self, 'pandas.series or string', 'self')

    if not isinstance(other, (SeriesType, types.Number, types.UnicodeType)):
        ty_checker.raise_exc(other, 'pandas.series or string', 'other')

    operands_are_series = self_is_series and other_is_series
    if operands_are_series:
        series_indexes_comparable = check_types_comparable(self.index, other.index)
        if not series_indexes_comparable:
            raise TypingError('{} Not implemented for series with not-comparable indexes. \
            Given: self.index={}, other.index={}'.format(_func_name, self.index, other.index))

    # check operation is allowed
    self_is_int_series = self_is_series and isinstance(self.dtype, types.Integer)
    other_is_int_series = other_is_series and isinstance(other.dtype, types.Integer)
    if not (self_is_string_series and (other_is_int_series or isinstance(other, types.Integer))
            or (other_is_string_series and (self_is_int_series or isinstance(self, types.Integer)))):
        raise TypingError('{} Not supported between operands of types: self={}, \
        other={}'.format(_func_name, self, other))

    if not operands_are_series:
        def _series_operator_mul_scalar_impl(self, other):
            if self_is_series == True:  # noqa
                result_data = self._data * other
                return pandas.Series(result_data, index=self._index, name=self._name)
            else:
                result_data = self * other._data
                return pandas.Series(result_data, index=other._index, name=other._name)

        return _series_operator_mul_scalar_impl
    else:   # both operands are series (one is integer and other is string)

        self_is_series = isinstance(self, SeriesType)
        # optimization for series with default indexes, that can be aligned differently
        if (isinstance(self.index, PositionalIndexType) and isinstance(other.index, PositionalIndexType)):
            def _series_operator_mul_none_indexes_impl(self, other):

                series_operand = self if self_is_series == True else other  # noqa
                if (len(self._data) == len(other._data)):
                    result_data = self._data * other._data
                    return pandas.Series(result_data)
                else:
                    left_size, right_size = len(self._data), len(other._data)
                    min_data_size = min(left_size, right_size)
                    max_data_size = max(left_size, right_size)

                    result_data_as_list = []
                    result_nan_mask = numpy.zeros(max_data_size, dtype=numpy.bool_)
                    result_nan_mask[min_data_size:] = True
                    for i in numpy.arange(min_data_size):
                        if str_arr_is_na(series_operand._data, i):
                            result_nan_mask[i] = True
                            result_data_as_list.append('')
                        result_data_as_list.append(self._data[i] * other._data[i])
                    result_data_as_list.extend([''] * (max_data_size - min_data_size))
                    result_data = create_str_arr_from_list(result_data_as_list)
                    str_arr_set_na_by_mask(result_data, result_nan_mask)

                    return pandas.Series(result_data, self._index)

            return _series_operator_mul_none_indexes_impl
        else:
            index_api_supported = not (isinstance(self.index, sdc_old_index_types)
                                       or isinstance(other.index, sdc_old_index_types))

            def _series_operator_mul_common_impl(self, other):
                left_index, right_index = self._index, other._index
                if index_api_supported == True:  # noqa
                    indexes_join_res = left_index.join(right_index, 'outer', return_indexers=True)
                else:
                    indexes_join_res = sdc_indexes_join_outer(left_index, right_index)

                # FIXME_Numba#XXXX: remove sdc_fix_indexes_join call at all when issue is fixed
                joined_index, left_indexer, right_indexer = sdc_fix_indexes_join(*indexes_join_res)
                str_series_operand = self if self_is_string_series == True else other  # noqa
                str_series_indexer = left_indexer if self_is_string_series == True else right_indexer  # noqa
                result_size = len(joined_index)
                result_nan_mask = numpy.zeros(result_size, dtype=numpy.bool_)
                result_data_as_list = []
                for i in numpy.arange(result_size):
                    if (left_indexer[i] == -1
                            or right_indexer[i] == -1
                            or str_arr_is_na(str_series_operand._data, str_series_indexer[i])):
                        result_nan_mask[i] = True
                        result_data_as_list.append('')
                    else:
                        result_data_as_list.append(self._data[left_indexer[i]] * other._data[right_indexer[i]])

                result_data = create_str_arr_from_list(result_data_as_list)
                str_arr_set_na_by_mask(result_data, result_nan_mask)

                return pandas.Series(result_data, joined_index)

            return _series_operator_mul_common_impl


@sdc_overload_method(SeriesType, 'groupby')
def sdc_pandas_series_groupby(self, by=None, axis=0, level=None, as_index=True, sort=True,
                              group_keys=True, squeeze=False, observed=False):
    """
    Intel Scalable Dataframe Compiler User Guide
    ********************************************

    Pandas API: pandas.Series.groupby

    Limitations
    -----------
    - Parameters ``axis``, ``level``, ``as_index``, ``group_keys``, ``squeeze`` and ``observed`` \
are currently unsupported by Intel Scalable Dataframe Compiler
    - Parameter ``by`` is supported as single literal column name only
    - Mutating the contents of a DataFrame between creating a groupby object and calling it's methods is unsupported

    Examples
    --------
    .. literalinclude:: ../../../examples/series/series_groupby.py
       :language: python
       :lines: 33-
       :caption: Return the mean of the values grouped by numpy array.
       :name: ex_series_groupby

    .. command-output:: python ./series/series_groupby.py
       :cwd: ../../../examples

    .. seealso::

        :ref:`Series.resample <pandas.Series.resample>`
            Resample time-series data.

    Intel Scalable Dataframe Compiler Developer Guide
    *************************************************
    Pandas Series method :meth:`pandas.Series.groupby` implementation.

    .. only:: developer
        Test: python -m sdc.runtests sdc.tests.test_groupby.TestGroupBy.test_series_groupby*
    """

    _func_name = 'Method Series.groupby().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    # we support only simpliest case of by being 1D array (a column of a DataFrame)
    # TODO: extend and support fully functional SeriesGroupBy
    if not ((isinstance(by, types.Array) and by.ndim == 1)
            or by == string_array_type):
        return None

    if not (isinstance(axis, (types.Integer, types.UnicodeType, types.Omitted)) or axis == 0):
        ty_checker.raise_exc(axis, 'int or str', 'axis')

    if not (level is None or isinstance(level, types.Omitted)):
        raise TypingError('{} Unsupported parameters. Given inplace: {}'.format(_func_name, level))

    if not (as_index is True or isinstance(as_index, types.Omitted)):
        raise TypingError('{} Unsupported parameters. Given inplace: {}'.format(_func_name, as_index))

    if not (isinstance(sort, (types.Omitted, types.Boolean)) or sort is True):
        ty_checker.raise_exc(sort, 'bool', 'sort')

    if not (group_keys is True or isinstance(group_keys, types.Omitted)):
        raise TypingError('{} Unsupported parameters. Given inplace: {}'.format(_func_name, group_keys))

    if not (squeeze is False or isinstance(squeeze, types.Omitted)):
        raise TypingError('{} Unsupported parameters. Given inplace: {}'.format(_func_name, squeeze))

    if not (observed is False or isinstance(observed, types.Omitted)):
        raise TypingError('{} Unsupported parameters. Given inplace: {}'.format(_func_name, observed))

    by_type = by.dtype
    list_type = types.ListType(types.int64)
    def sdc_pandas_series_groupby_impl(self, by=None, axis=0, level=None, as_index=True, sort=True,
                                       group_keys=True, squeeze=False, observed=False):

        if len(self) != len(by):
            raise ValueError("Series.groupby(). Grouper and axis must be same length")

        grouped = Dict.empty(by_type, list_type)
        for i in numpy.arange(len(by)):
            if isna(by, i):
                continue
            value = by[i]
            group_list = grouped.get(value, List.empty_list(types.int64))
            group_list.append(i)
            grouped[value] = group_list

        return init_series_groupby(self, by, grouped, sort)

    return sdc_pandas_series_groupby_impl


@sdc_overload_method(SeriesType, 'skew')
def sdc_pandas_series_skew(self, axis=None, skipna=None, level=None, numeric_only=None):
    """
        Intel Scalable Dataframe Compiler User Guide
        ********************************************

        Pandas API: pandas.Series.skew

        Limitations
        -----------
        - Parameters ``level`` and ``numeric_only`` are supported only with default value ``None``.

        Examples
        --------
        .. literalinclude:: ../../../examples/series/series_skew.py
           :language: python
           :lines: 27-
           :caption: Unbiased rolling skewness.
           :name: ex_series_skew

        .. command-output:: python ./series/series_skew.py
           :cwd: ../../../examples

        Intel Scalable Dataframe Compiler Developer Guide
        *************************************************
        Pandas Series method :meth:`pandas.Series.skew` implementation.

        .. only:: developer
            Test: python -m sdc.runtests -k sdc.tests.test_series.TestSeries.test_series_skew*
        """
    _func_name = 'Method Series.skew().'

    ty_checker = TypeChecker(_func_name)
    ty_checker.check(self, SeriesType)

    if not isinstance(axis, (types.Integer, types.NoneType, types.Omitted)) and axis is not None:
        ty_checker.raise_exc(axis, 'int64', 'axis')

    if not isinstance(skipna, (types.Boolean, types.NoneType, types.Omitted)) and skipna is not None:
        ty_checker.raise_exc(skipna, 'bool', 'skipna')

    if not isinstance(level, (types.Omitted, types.NoneType)) and level is not None:
        ty_checker.raise_exc(level, 'None', 'level')

    if not isinstance(numeric_only, (types.Omitted, types.NoneType)) and numeric_only is not None:
        ty_checker.raise_exc(numeric_only, 'None', 'numeric_only')

    def sdc_pandas_series_skew_impl(self, axis=None, skipna=None, level=None, numeric_only=None):
        if axis != 0 and axis is not None:
            raise ValueError('Parameter axis must be only 0 or None.')

        if skipna is None:
            _skipna = True
        else:
            _skipna = skipna

        if _skipna:
            return numpy_like.nanskew(self._data)

        return numpy_like.skew(self._data)

    return sdc_pandas_series_skew_impl
