import sys
import math
import itertools

from collections import defaultdict, namedtuple
from types import SimpleNamespace as namespace

import numpy as np
import scipy.sparse as sp

from AnyQt.QtWidgets import (
    QSizePolicy, QGraphicsScene, QGraphicsView, QGraphicsRectItem,
    QGraphicsWidget, QGraphicsSimpleTextItem, QGraphicsPixmapItem,
    QGraphicsGridLayout, QGraphicsLinearLayout, QGraphicsLayoutItem,
    QFormLayout, QApplication
)
from AnyQt.QtGui import (
    QFontMetrics, QPen, QPixmap, QColor, QLinearGradient, QPainter,
    QTransform, QIcon, QBrush,
    QStandardItemModel, QStandardItem,
)
from AnyQt.QtCore import (
    Qt, QSize, QPointF, QSizeF, QRectF, QObject, QEvent,
    pyqtSignal as Signal,
)
import pyqtgraph as pg

from Orange.data import Domain, Table, DiscreteVariable, StringVariable
from Orange.data.sql.table import SqlTable
import Orange.distance

from Orange.clustering import hierarchical
from Orange.widgets.utils import colorbrewer
from Orange.widgets.utils.annotated_data import (create_annotated_table,
                                                 ANNOTATED_DATA_SIGNAL_NAME)
from Orange.widgets import widget, gui, settings

from Orange.widgets.unsupervised.owhierarchicalclustering import \
    DendrogramWidget

from Orange.widgets.widget import Msg


def split_domain(domain, split_label):
    """Split the domain based on values of `split_label` value.
    """
    groups = defaultdict(list)
    for attr in domain.attributes:
        groups[attr.attributes.get(split_label)].append(attr)

    attr_values = [attr.attributes.get(split_label)
                   for attr in domain.attributes]

    domains = []
    for value, attrs in groups.items():
        group_domain = Domain(attrs, domain.class_vars, domain.metas)

        domains.append((value, group_domain))

    if domains:
        assert all(len(dom) == len(domains[0][1]) for _, dom in domains)

    return sorted(domains, key=lambda t: attr_values.index(t[0]))


def vstack_by_subdomain(data, sub_domains):
    domain = sub_domains[0]
    newtable = Table(domain)

    for sub_dom in sub_domains:
        sub_data = data.from_table(sub_dom, data)
        # TODO: improve O(N ** 2)
        newtable.extend(sub_data)

    return newtable


def select_by_class(data, class_):
    indices = select_by_class_indices(data, class_)
    return data[indices]


def select_by_class_indices(data, class_):
    col, _ = data.get_column_view(data.domain.class_var)
    return col == class_


def group_by_unordered(iterable, key):
    groups = defaultdict(list)
    for item in iterable:
        groups[key(item)].append(item)
    return groups.items()


def barycenter(a, axis=0):
    assert 0 <= axis < 2
    a = np.asarray(a)
    N = a.shape[axis]
    tileshape = [1 if i != axis else a.shape[i] for i in range(a.ndim)]
    xshape = list(a.shape)
    xshape[axis] = 1
    X = np.tile(np.reshape(np.arange(N), tileshape), xshape)
    amin = np.nanmin(a, axis=axis, keepdims=True)
    weights = a - amin
    weights[np.isnan(weights)] = 0
    wsum = np.sum(weights, axis=axis)
    mask = wsum <= np.finfo(float).eps
    if axis == 1:
        weights[mask, :] = 1
    else:
        weights[:, mask] = 1

    return np.average(X, weights=weights, axis=axis)

from Orange.clustering import kmeans


def kmeans_compress(X, k=50):
    km = kmeans.KMeans(n_clusters=k, n_init=5, random_state=42)
    return km(X)


def candidate_split_labels(data):
    """
    Return candidate labels on which we can split the data.
    """
    groups = defaultdict(list)
    for attr in data.domain.attributes:
        for item in attr.attributes.items():
            groups[item].append(attr)

    by_keys = defaultdict(list)
    for (key, _), attrs in groups.items():
        by_keys[key].append(attrs)

    # Find the keys for which all values have the same number
    # of attributes.
    candidates = []
    for key, groups in by_keys.items():
        count = len(groups[0])
        if all(len(attrs) == count for attrs in groups) and \
                len(groups) > 1 and count > 1:
            candidates.append(key)

    return candidates


def leaf_indices(tree):
    return [leaf.value.index for leaf in hierarchical.leaves(tree)]


def palette_gradient(colors, discrete=False):
    n = len(colors)
    stops = np.linspace(0.0, 1.0, n, endpoint=True)
    gradstops = [(float(stop), color) for stop, color in zip(stops, colors)]
    grad = QLinearGradient(QPointF(0, 0), QPointF(1, 0))
    grad.setStops(gradstops)
    return grad


def palette_pixmap(colors, size):
    img = QPixmap(size)
    img.fill(Qt.transparent)

    grad = palette_gradient(colors)
    grad.setCoordinateMode(QLinearGradient.ObjectBoundingMode)

    painter = QPainter(img)
    painter.setPen(Qt.NoPen)
    painter.setBrush(QBrush(grad))
    painter.drawRect(0, 0, size.width(), size.height())
    painter.end()
    return img


def color_palette_model(palettes, iconsize=QSize(64, 16)):
    model = QStandardItemModel()
    for name, palette in palettes:
        _, colors = max(palette.items())
        colors = [QColor(*c) for c in colors]
        item = QStandardItem(name)
        item.setIcon(QIcon(palette_pixmap(colors, iconsize)))
        item.setData(palette, Qt.UserRole)
        model.appendRow([item])
    return model


def color_palette_table(colors, samples=255,
                        threshold_low=0.0, threshold_high=1.0,
                        underflow=None, overflow=None,
                        gamma=None):
    N = len(colors)
    colors = np.array(colors, dtype=np.ubyte)
    low, high = threshold_low * 255, threshold_high * 255
    points = np.linspace(low, high, N)
    space = np.linspace(0, 255, 255)

    if underflow is None:
        underflow = [None, None, None]

    if overflow is None:
        overflow = [None, None, None]

    if gamma is None or gamma < 0.0001:
        r = np.interp(space, points, colors[:, 0],
                      left=underflow[0], right=overflow[0])
        g = np.interp(space, points, colors[:, 1],
                      left=underflow[1], right=overflow[1])
        b = np.interp(space, points, colors[:, 2],
                      left=underflow[2], right=overflow[2])
    else:
        r = interp_exp(space, points, colors[:, 0], gamma=gamma,
                       left=underflow[0], right=overflow[0])
        g = interp_exp(space, points, colors[:, 1], gamma=gamma,
                       left=underflow[0], right=overflow[0])
        b = interp_exp(space, points, colors[:, 2], gamma=gamma,
                       left=underflow[0], right=overflow[0])
    return np.c_[r, g, b]


def interp_exp(x, xp, fp, gamma=0.0, left=None, right=None,):
    assert np.all(np.diff(xp) > 0)
    x = np.asanyarray(x)
    xp = np.asanyarray(xp)
    fp = np.asanyarray(fp)

    if xp.shape != fp.shape:
        raise ValueError("xp and fp must have the same shape")

    ind = np.searchsorted(xp, x, side="right")

    f = np.zeros(len(x))

    under = ind == 0
    over = ind == len(xp)
    between = ~under & ~over

    f[under] = left if left is not None else fp[0]
    f[over] = right if right is not None else fp[-1]

    if right is not None:
        # Fix points exactly on the right boundary.
        f[x == xp[-1]] = fp[-1]

    ind = ind[between]

    def exp_ramp(x, gamma):
        assert gamma >= 0
        if gamma < np.finfo(float).eps:
            return x
        else:
            return (np.exp(gamma * x) - 1) / (np.exp(gamma) - 1.)

    def gamma_fun(x, gamma):
        out = np.array(x)
        out[x < 0.5] = exp_ramp(x[x < 0.5] * 2, gamma) / 2
        out[x > 0.5] = 1 - exp_ramp((1 - x[x > 0.5]) * 2, gamma) / 2
        return out

    y0, y1 = fp[ind - 1], fp[ind]
    x0, x1 = xp[ind - 1], xp[ind]

    m = (x[between] - x0) / (x1 - x0)
    m = gamma_fun(m, gamma)
    f[between] = (1 - m) * y0 + m * y1

    return f

# TODO:
#     * Richer Tool Tips
#     * Color map edit/manage
#     * Restore saved row selection (?)
#     * 'namespace' use cleanup

# Heatmap grid description
# ########################
#
# Heatmaps can be split vertically (by discrete var) and/or horizontaly
# (by suitable variable labels).
# Each vertical split has a title (split variable value) and can
# be sorted/clustred individually. Horizontal splits can also be
# clustered but will share the same cluster)


RowPart = namedtuple(
    "RowPart",
    ["title",
     "indices",
     "sortindices",
     "cluster",
     "cluster_ordered"]
)


class RowPart(RowPart):
    """
    A row group

    Attributes
    ----------
    title: str
        Group title
    indices : (N, ) int ndarray | slice
        Indexes the input data to retrieve the row subset for the group.
    sortindices : (N, ) int ndarray
        Sort indices which sort data[self.indices] by 'barycentric' method
    cluster : hierarchical.Tree optional
    cluster_ordered : hierarchical.Tree optional
    """
    def __new__(cls, title, indices, sortindices, cluster=None,
                cluster_ordered=None):
        if isinstance(indices, slice):
            assert indices.start is not None and indices.stop is not None \
                   and indices.start <= indices.stop \
                   and (indices.step == 1 or indices.step is None)
        return super().__new__(cls, title, indices, sortindices,
                               cluster, cluster_ordered)

    @property
    def is_empty(self):
        if isinstance(self.indices, slice):
            return (self.indices.stop - self.indices.start) == 0
        else:
            return len(self.indices) == 0

    @property
    def cluster_ord(self):
        return self.cluster_ordered


ColumnPart = namedtuple(
    "ColumnPart",
    ["title",    #: str
     "indices",  #: indices
     "domain",   #: list of Variable
     "cluster",  #: hierarchical.Tree option
     "cluster_ordered",  #: hierarchical.Tree option
    ]
)


class ColumnPart(ColumnPart):
    """
    A column group

    Attributes
    ----------
    title : str
        Column group title
    indices : (N, ) int ndarray | slice
        Indexes the input data to retrieve the column subset for the group.
    domain : List[Variable]
        List of variables in the group.
    cluster : hierarchical.Tree optional
    cluster_ordered : hierarchical.Tree optional
    """
    def __new__(cls, title, indices, domain, cluster=None,
                cluster_ordered=None):
        return super().__new__(cls, title, indices, domain, cluster,
                               cluster_ordered)

    @property
    def cluster_ord(self):
        return self.cluster_ordered


Parts = namedtuple(
    "Parts",
    ["rows",     #: A list of RowPart descriptors
     "columns",  #: A list of ColumnPart descriptors
     "span",     #: (min, max) global data range
    ]
)

Parts.levels = property(lambda self: self.span)


_color_palettes = (sorted(colorbrewer.colorSchemes["sequential"].items()) +
                   [("Blue-Yellow", {2: [(0, 0, 255), (255, 255, 0)]}),
                    ("Green-Black-Red", {3: [(0, 255, 0), (0, 0, 0),
                                             (255, 0, 0)]})])
_default_palette_index = \
    [name for name, _, in _color_palettes].index("Blue-Yellow")


class OWHeatMap(widget.OWWidget):
    name = "Heat Map"
    description = "Plot a heat map for a pair of attributes."
    icon = "icons/Heatmap.svg"
    priority = 260

    inputs = [("Data", Table, "set_dataset")]
    outputs = [("Selected Data", Table, widget.Default),
               (ANNOTATED_DATA_SIGNAL_NAME, Table)]

    settingsHandler = settings.DomainContextHandler()

    NoPosition, PositionTop, PositionBottom = 0, 1, 2

    # Disable cluster leaf ordering for inputs bigger than this
    _MaxOrderedClustering = 1000

    gamma = settings.Setting(0)
    threshold_low = settings.Setting(0.0)
    threshold_high = settings.Setting(1.0)

    merge_kmeans = settings.Setting(False)
    merge_kmeans_k = settings.Setting(50)

    # Display stripe with averages
    averages = settings.Setting(True)
    # Display legend
    legend = settings.Setting(True)
    # Annotations
    annotation_index = settings.ContextSetting(0)
    # Stored color palette settings
    color_settings = settings.Setting(None)
    user_palettes = settings.Setting([])

    col_clustering = settings.Setting(False)
    row_clustering = settings.Setting(False)

    palette_index = settings.Setting(_default_palette_index)
    column_label_pos = settings.Setting(PositionTop)

    auto_commit = settings.Setting(True)

    graph_name = "scene"

    class Information(widget.OWWidget.Information):
        sampled = Msg("Data has been sampled")
        discrete_ignored = Msg("{} discrete column{} ignored")
        row_clust = Msg("{}")
        col_clust = Msg("{}")
        sparse_densified = Msg("Showing this data may require a lot of memory")

    class Error(widget.OWWidget.Error):
        no_continuous = Msg("No continuous feature columns")
        not_enough_features = Msg("Not enough features for column clustering")
        not_enough_instances = Msg("Not enough instances for clustering")
        not_enough_instances_k_means = Msg(
            "Not enough instances for k-means merging")
        not_enough_memory = Msg("Not enough memory to show this data")

    def __init__(self):
        super().__init__()

        # set default settings
        self.SpaceX = 10

        self.colorSettings = None
        self.selectedSchemaIndex = 0

        self.palette = None
        self.keep_aspect = False

        #: The original data with all features (retained to
        #: preserve the domain on the output)
        self.input_data = None
        #: The effective data striped of discrete features, and often
        #: merged using k-means
        self.data = None
        self.effective_data = None
        #: kmeans model used to merge rows of input_data
        self.kmeans_model = None
        #: merge indices derived from kmeans
        #: a list (len==k) of int ndarray where the i-th item contains
        #: the indices which merge the input_data into the heatmap row i
        self.merge_indices = None

        self.annotation_vars = ['(None)']
        self.__rows_cache = {}
        self.__columns_cache = {}

        # GUI definition
        colorbox = gui.vBox(self.controlArea, "Color")
        self.color_cb = gui.comboBox(colorbox, self, "palette_index")
        self.color_cb.setIconSize(QSize(64, 16))
        palettes = _color_palettes + self.user_palettes

        self.palette_index = min(self.palette_index, len(palettes) - 1)

        model = color_palette_model(palettes, self.color_cb.iconSize())
        model.setParent(self)
        self.color_cb.setModel(model)
        self.color_cb.activated.connect(self.update_color_schema)

        self.color_cb.setCurrentIndex(self.palette_index)
        # TODO: Add 'Manage/Add/Remove' action.

        form = QFormLayout(
            formAlignment=Qt.AlignLeft,
            labelAlignment=Qt.AlignLeft,
            fieldGrowthPolicy=QFormLayout.AllNonFixedFieldsGrow
        )

        lowslider = gui.hSlider(
            colorbox, self, "threshold_low", minValue=0.0, maxValue=1.0,
            step=0.05, ticks=True, intOnly=False,
            createLabel=False, callback=self.update_lowslider)
        highslider = gui.hSlider(
            colorbox, self, "threshold_high", minValue=0.0, maxValue=1.0,
            step=0.05, ticks=True, intOnly=False,
            createLabel=False, callback=self.update_highslider)
        gammaslider = gui.hSlider(
            colorbox, self, "gamma", minValue=0.0, maxValue=20.0,
            step=1.0, ticks=True, intOnly=False,
            createLabel=False, callback=self.update_color_schema
        )

        form.addRow("Low:", lowslider)
        form.addRow("High:", highslider)
        form.addRow("Gamma:", gammaslider)

        colorbox.layout().addLayout(form)

        mergebox = gui.vBox(self.controlArea, "Merge",)
        gui.checkBox(mergebox, self, "merge_kmeans", "Merge by k-means",
                     callback=self.update_sorting_examples)
        ibox = gui.indentedBox(mergebox)
        gui.spin(ibox, self, "merge_kmeans_k", minv=5, maxv=500,
                 label="Clusters:", keyboardTracking=False,
                 callbackOnReturn=True, callback=self.update_merge)

        cluster_box = gui.vBox(self.controlArea, "Cluster")
        self.col_check = gui.checkBox(
            cluster_box, self, "col_clustering", "Columns",
            callback=self.update_clustering_examples)
        self.row_check = gui.checkBox(
            cluster_box, self, "row_clustering", "Rows",
            callback=self.update_clustering_examples)

        box = gui.vBox(self.controlArea, 'Annotation && Legends')

        gui.checkBox(box, self, 'legend', 'Show legend',
                     callback=self.update_legend)

        gui.checkBox(box, self, 'averages', 'Stripes with averages',
                     callback=self.update_averages_stripe)

        annotbox = gui.vBox(box, "Row Annotations", addSpace=False)
        annotbox.setFlat(True)
        self.annotations_cb = gui.comboBox(annotbox, self, "annotation_index",
                                           items=self.annotation_vars,
                                           callback=self.update_annotations)

        posbox = gui.vBox(box, "Column Labels Position", addSpace=False)
        posbox.setFlat(True)

        gui.comboBox(
            posbox, self, "column_label_pos",
            items=["None", "Top", "Bottom", "Top and Bottom"],
            callback=self.update_column_annotations)

        gui.checkBox(self.controlArea, self, "keep_aspect",
                     "Keep aspect ratio", box="Resize",
                     callback=self.__aspect_mode_changed)

        gui.rubber(self.controlArea)
        gui.auto_commit(self.controlArea,
                        self,
                        "auto_commit",
                        "Send Selection",
                        "Send Automatically"
                       )

        # Scene with heatmap
        self.heatmap_scene = self.scene = HeatmapScene(parent=self)
        self.selection_manager = HeatmapSelectionManager(self)
        self.selection_manager.selection_changed.connect(
            self.__update_selection_geometry)
        self.selection_manager.selection_finished.connect(
            self.on_selection_finished)
        self.heatmap_scene.set_selection_manager(self.selection_manager)

        item = QGraphicsRectItem(0, 0, 10, 10, None)
        self.heatmap_scene.addItem(item)
        self.heatmap_scene.itemsBoundingRect()
        self.heatmap_scene.removeItem(item)

        self.sceneView = QGraphicsView(
            self.scene,
            verticalScrollBarPolicy=Qt.ScrollBarAlwaysOn,
            horizontalScrollBarPolicy=Qt.ScrollBarAlwaysOn,
            viewportUpdateMode=QGraphicsView.FullViewportUpdate,
        )

        self.sceneView.viewport().installEventFilter(self)

        self.mainArea.layout().addWidget(self.sceneView)
        self.heatmap_scene.widget = None

        self.heatmap_widget_grid = [[]]
        self.attr_annotation_widgets = []
        self.attr_dendrogram_widgets = []
        self.gene_annotation_widgets = []
        self.gene_dendrogram_widgets = []

        self.selection_rects = []
        self.selected_rows = []

    def sizeHint(self):
        return QSize(800, 400)

    def color_palette(self):
        data = self.color_cb.itemData(self.palette_index, role=Qt.UserRole)
        if data is None:
            return []
        else:
            _, colors = max(data.items())
            return color_palette_table(
                colors, threshold_low=self.threshold_low,
                threshold_high=self.threshold_high,
                gamma=self.gamma)

    def clear(self):
        self.data = None
        self.input_data = None
        self.effective_data = None
        self.kmeans_model = None
        self.merge_indices = None
        self.annotations_cb.clear()
        self.annotations_cb.addItem('(None)')
        self.annotation_vars = ['(None)']
        self.clear_scene()
        self.selected_rows = []
        self.__columns_cache.clear()
        self.__rows_cache.clear()
        self.__update_clustering_enable_state(None)

    def clear_scene(self):
        self.selection_manager.set_heatmap_widgets([[]])
        self.heatmap_scene.clear()
        self.heatmap_scene.widget = None
        self.heatmap_widget_grid = [[]]
        self.col_annotation_widgets = []
        self.col_annotation_widgets_bottom = []
        self.col_annotation_widgets_top = []
        self.row_annotation_widgets = []
        self.col_dendrograms = []
        self.row_dendrograms = []
        self.selection_rects = []

    def set_dataset(self, data=None):
        """Set the input dataset to display."""
        self.closeContext()
        self.clear()
        self.clear_messages()

        if isinstance(data, SqlTable):
            if data.approx_len() < 4000:
                data = Table(data)
            else:
                self.Information.sampled()
                data_sample = data.sample_time(1, no_cache=True)
                data_sample.download_data(2000, partial=True)
                data = Table(data_sample)

        if data is not None and not len(data):
            data = None

        if data is not None and sp.issparse(data.X):
            try:
                data = data.copy()
                data.X = data.X.toarray()
            except MemoryError:
                data = None
                self.Error.not_enough_memory()
            else:
                self.Information.sparse_densified()

        input_data = data

        # Data contains no attributes or meta attributes only
        if data is not None and len(data.domain.attributes) == 0:
            self.Error.no_continuous()
            input_data = data = None

        # Data contains some discrete attributes which must be filtered
        if data is not None and \
                any(var.is_discrete for var in data.domain.attributes):
            ndisc = sum(var.is_discrete for var in data.domain.attributes)
            data = data.from_table(
                Domain([var for var in data.domain.attributes
                        if var.is_continuous],
                       data.domain.class_vars,
                       data.domain.metas),
                data)
            if not data.domain.attributes:
                self.Error.no_continuous()
                input_data = data = None
            else:
                self.Information.discrete_ignored(
                    ndisc, "s" if ndisc > 1 else "")

        self.data = data
        self.input_data = input_data

        if data is not None:
            variables = self.data.domain.class_vars + self.data.domain.metas
            variables = [var for var in variables
                         if isinstance(var, (DiscreteVariable, StringVariable))]
            self.annotation_vars.extend(variables)

            for var in variables:
                self.annotations_cb.addItem(*gui.attributeItem(var))

            self.openContext(self.data)
            if self.annotation_index >= len(self.annotation_vars):
                self.annotation_index = 0
        self.update_heatmaps()

    def update_heatmaps(self):
        if self.data is not None:
            self.clear_scene()
            self.clear_messages()
            if self.col_clustering and len(self.data.domain.attributes) < 2:
                self.Error.not_enough_features()
            elif (self.col_clustering or self.row_clustering) and \
                    len(self.data) < 2:
                self.Error.not_enough_instances()
            elif self.merge_kmeans and len(self.data) < 3:
                self.Error.not_enough_instances_k_means()
            else:
                self.construct_heatmaps(self.data)
                self.construct_heatmaps_scene(
                    self.heatmapparts, self.effective_data)
                self.selected_rows = []
        else:
            self.clear()
        self.commit()

    def update_merge(self):
        self.kmeans_model = None
        self.merge_indices = None
        if self.data is not None and self.merge_kmeans:
            self.update_heatmaps()

    def _make_parts(self, data, group_var=None, group_key=None):
        """
        Make initial `Parts` for data, split by group_var, group_key
        """
        if group_var is not None:
            assert group_var.is_discrete
            _col_data, _ = data.get_column_view(group_var)
            row_indices = [np.flatnonzero(_col_data == i)
                           for i in range(len(group_var.values))]
            row_groups = [RowPart(title=name, indices=ind, sortindices=None,
                                  cluster=None, cluster_ordered=None)
                          for name, ind in zip(group_var.values, row_indices)]
        else:
            row_groups = [RowPart(title=None, indices=slice(0, len(data)),
                                  sortindices=None,
                                  cluster=None, cluster_ordered=None)]

        if group_key is not None:
            col_groups = split_domain(data.domain, group_key)
            assert len(col_groups) > 0
            col_indices = [np.array([data.domain.index(var) for var in group])
                           for _, group in col_groups]
            col_groups = [ColumnPart(title=name, domain=d, indices=ind,
                                     cluster=None, cluster_ordered=None)
                          for (name, d), ind in zip(col_groups, col_indices)]
        else:
            col_groups = [
                ColumnPart(
                    title=None, indices=slice(0, len(data.domain.attributes)),
                    domain=data.domain, cluster=None, cluster_ordered=None)
            ]

        minv, maxv = np.nanmin(data.X), np.nanmax(data.X)
        return Parts(row_groups, col_groups, span=(minv, maxv))

    def cluster_rows(self, data, parts):
        row_groups = []
        for row in parts.rows:
            if row.cluster is not None:
                cluster = row.cluster
            else:
                cluster = None
            if row.cluster_ordered is not None:
                cluster_ord = row.cluster_ordered
            else:
                cluster_ord = None

            if not row.is_empty:
                need_dist = cluster is None or cluster_ord is None
                if need_dist:
                    subset = data[row.indices]
                    subset = Orange.distance._preprocess(subset)
                    matrix = Orange.distance.Euclidean(subset)

                if cluster is None:
                    cluster = hierarchical.dist_matrix_clustering(matrix)

                if cluster_ord is None:
                    with self.progressBar():
                        cluster_ord = hierarchical.optimal_leaf_ordering(
                            cluster, matrix,
                            progress_callback=self.progressBarSet)

            row_groups.append(row._replace(cluster=cluster, cluster_ordered=cluster_ord))

        return parts._replace(columns=parts.columns, rows=row_groups)

    def cluster_columns(self, data, parts):
        if len(parts.columns) > 1:
            data = vstack_by_subdomain(data, [col.domain for col in parts.columns])
        assert all(var.is_continuous for var in data.domain.attributes)

        col0 = parts.columns[0]
        if col0.cluster is not None:
            cluster = col0.cluster
        else:
            cluster = None
        if col0.cluster_ord is not None:
            cluster_ord = col0.cluster_ord
        else:
            cluster_ord = None
        need_dist = cluster is None or cluster_ord is None

        if need_dist:
            data = Orange.distance._preprocess(data)
            matrix = Orange.distance.PearsonR(data, axis=0)

        if cluster is None:
            cluster = hierarchical.dist_matrix_clustering(matrix)
        if cluster_ord is None:
            with self.progressBar():
                cluster_ord = hierarchical.optimal_leaf_ordering(
                    cluster, matrix, progress_callback=self.progressBarSet)

        col_groups = [col._replace(cluster=cluster, cluster_ordered=cluster_ord)
                      for col in parts.columns]
        return parts._replace(columns=col_groups, rows=parts.rows)

    def construct_heatmaps(self, data, split_label=None):
        if split_label is not None:
            groups = split_domain(data.domain, split_label)
            assert len(groups) > 0
        else:
            groups = [("", data.domain)]

        if data.domain.has_discrete_class:
            group_var = data.domain.class_var
        else:
            group_var = None

        group_label = split_label
        if self.merge_kmeans:
            if self.kmeans_model is None:
                effective_data = self.input_data.from_table(
                    Orange.data.Domain(
                        [var for var in self.input_data.domain.attributes
                         if var.is_continuous],
                        self.input_data.domain.class_vars,
                        self.input_data.domain.metas),
                    self.input_data
                )
                nclust = min(self.merge_kmeans_k, len(effective_data) - 1)
                self.kmeans_model = kmeans_compress(effective_data, k=nclust)
                effective_data.domain = self.kmeans_model.pre_domain
                self.merge_indices = [np.flatnonzero(self.kmeans_model.labels_ == ind)
                                      for ind in range(nclust)]
                effective_data = Orange.data.Table(
                    Orange.data.Domain(effective_data.domain.attributes),
                    self.kmeans_model.centroids
                )
            else:
                effective_data = self.effective_data

            group_var = None
        else:
            self.kmeans_model = None
            self.merge_indices = None
            effective_data = data

        self.effective_data = effective_data

        self.__update_clustering_enable_state(effective_data)

        parts = self._make_parts(effective_data, group_var, group_label)
        # Restore/update the row/columns items descriptions from cache if
        # available
        rows_cache_key = (group_var,
                          self.merge_kmeans_k if self.merge_kmeans else None)
        if rows_cache_key in self.__rows_cache:
            parts = parts._replace(rows=self.__rows_cache[rows_cache_key].rows)

        if group_label in self.__columns_cache:
            parts = parts._replace(
                columns=self.__columns_cache[group_label].columns)

        if self.row_clustering:
            assert len(effective_data) <= OWHeatMap._MaxOrderedClustering
            parts = self.cluster_rows(effective_data, parts)

        if self.col_clustering:
            assert len(effective_data.domain.attributes) <= \
                   OWHeatMap._MaxOrderedClustering
            parts = self.cluster_columns(effective_data, parts)

        # Cache the updated parts
        self.__rows_cache[rows_cache_key] = parts
        self.__columns_cache[group_label] = parts

        self.heatmapparts = parts

    def construct_heatmaps_scene(self, parts, data):
        def select_row(item):
            return namespace(
                title=item.title, indices=item.indices,
                cluster=item.cluster_ord if self.row_clustering else None)

        def select_col(item):
            return namespace(
                title=item.title, indices=item.indices, domain=item.domain,
                cluster=item.cluster_ord if self.col_clustering else None)

        rows = [select_row(rowitem) for rowitem in parts.rows]
        cols = [select_col(colitem) for colitem in parts.columns]
        parts = namespace(columns=cols, rows=rows, levels=parts.levels)

        self.setup_scene(parts, data)

    def setup_scene(self, parts, data):
        # parts = * a list of row descriptors (title, indices, cluster,)
        #         * a list of col descriptors (title, indices, cluster, domain)
        self.heatmap_scene.clear()
        # The top level container widget
        widget = GraphicsWidget()
        widget.layoutDidActivate.connect(self.__update_selection_geometry)

        grid = QGraphicsGridLayout()
        grid.setSpacing(self.SpaceX)
        self.heatmap_scene.addItem(widget)

        N, M = len(parts.rows), len(parts.columns)

        # Start row/column where the heatmap items are inserted
        # (after the titles/legends/dendrograms)
        Row0 = 3
        Col0 = 3
        LegendRow = 0
        # The column for the vertical dendrogram
        DendrogramColumn = 0
        # The row for the horizontal dendrograms
        DendrogramRow = 1
        RightLabelColumn = Col0 + M
        TopLabelsRow = 2
        BottomLabelsRow = Row0 + 2 * N

        widget.setLayout(grid)

        palette = self.color_palette()

        sort_i = []
        sort_j = []

        column_dendrograms = [None] * M
        row_dendrograms = [None] * N

        for i, rowitem in enumerate(parts.rows):
            if rowitem.title:
                title = QGraphicsSimpleTextItem(rowitem.title, widget)
                item = GraphicsSimpleTextLayoutItem(title, parent=grid)
                grid.addItem(item, Row0 + i * 2, Col0)

            if rowitem.cluster:
                dendrogram = DendrogramWidget(
                    parent=widget,
                    selectionMode=DendrogramWidget.NoSelection,
                    hoverHighlightEnabled=True)
                dendrogram.set_root(rowitem.cluster)
                dendrogram.setMaximumWidth(100)
                dendrogram.setMinimumWidth(100)
                # Ignore dendrogram vertical size hint (heatmap's size
                # should define the  row's vertical size).
                dendrogram.setSizePolicy(
                    QSizePolicy.Expanding, QSizePolicy.Ignored)
                dendrogram.itemClicked.connect(
                    lambda item, partindex=i:
                    self.__select_by_cluster(item, partindex)
                )

                grid.addItem(dendrogram, Row0 + i * 2 + 1, DendrogramColumn)
                sort_i.append(np.array(leaf_indices(rowitem.cluster)))
                row_dendrograms[i] = dendrogram
            else:
                sort_i.append(None)

        for j, colitem in enumerate(parts.columns):
            if colitem.title:
                title = QGraphicsSimpleTextItem(colitem.title, widget)
                item = GraphicsSimpleTextLayoutItem(title, parent=grid)
                grid.addItem(item, 1, Col0 + j)

            if colitem.cluster:
                dendrogram = DendrogramWidget(
                    parent=widget,
                    orientation=DendrogramWidget.Top,
                    selectionMode=DendrogramWidget.NoSelection,
                    hoverHighlightEnabled=False)

                dendrogram.set_root(colitem.cluster)
                dendrogram.setMaximumHeight(100)
                dendrogram.setMinimumHeight(100)
                # Ignore dendrogram horizontal size hint (heatmap's width
                # should define the column width).
                dendrogram.setSizePolicy(
                    QSizePolicy.Ignored, QSizePolicy.Expanding)
                grid.addItem(dendrogram, DendrogramRow, Col0 + j)
                sort_j.append(np.array(leaf_indices(colitem.cluster)))
                column_dendrograms[j] = dendrogram
            else:
                sort_j.append(None)

        heatmap_widgets = []
        for i in range(N):
            heatmap_row = []
            for j in range(M):
                row_ix = parts.rows[i].indices
                col_ix = parts.columns[j].indices
                hw = GraphicsHeatmapWidget(parent=widget)
                X_part = data[row_ix, col_ix].X

                if sort_i[i] is not None:
                    X_part = X_part[sort_i[i]]
                if sort_j[j] is not None:
                    X_part = X_part[:, sort_j[j]]

                hw.set_levels(parts.levels)
                hw.set_color_table(palette)
                hw.set_show_averages(self.averages)
                hw.set_heatmap_data(X_part)

                grid.addItem(hw, Row0 + i * 2 + 1, Col0 + j)
                grid.setRowStretchFactor(Row0 + i * 2 + 1, X_part.shape[0] * 100)
                heatmap_row.append(hw)
            heatmap_widgets.append(heatmap_row)

        row_annotation_widgets = []
        col_annotation_widgets = []
        col_annotation_widgets_top = []
        col_annotation_widgets_bottom = []

        for i, rowitem in enumerate(parts.rows):
            if isinstance(rowitem.indices, slice):
                indices = np.array(
                    range(*rowitem.indices.indices(data.X.shape[0])))
            else:
                indices = rowitem.indices
            if sort_i[i] is not None:
                indices = indices[sort_i[i]]

            labels = [str(i) for i in indices]

            labelslist = GraphicsSimpleTextList(
                labels, parent=widget, orientation=Qt.Vertical)

            labelslist._indices = indices
            labelslist.setAlignment(Qt.AlignLeft | Qt.AlignVCenter)
            labelslist.setContentsMargins(0.0, 0.0, 0.0, 0.0)
            labelslist.setSizePolicy(QSizePolicy.Fixed, QSizePolicy.Expanding)

            grid.addItem(labelslist, Row0 + i * 2 + 1, RightLabelColumn)
            grid.setAlignment(labelslist, Qt.AlignLeft)
            row_annotation_widgets.append(labelslist)

        for j, colitem in enumerate(parts.columns):
            # Top attr annotations
            if isinstance(colitem.indices, slice):
                indices = np.array(
                    range(*colitem.indices.indices(data.X.shape[1])))
            else:
                indices = colitem.indices
            if sort_j[j] is not None:
                indices = indices[sort_j[j]]

            labels = [data.domain[i].name for i in indices]

            labelslist = GraphicsSimpleTextList(
                labels, parent=widget, orientation=Qt.Horizontal)
            labelslist.setAlignment(Qt.AlignBottom | Qt.AlignLeft)
            labelslist._indices = indices

            labelslist.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Fixed)

            grid.addItem(labelslist, TopLabelsRow, Col0 + j,
                         Qt.AlignBottom | Qt.AlignLeft)
            col_annotation_widgets.append(labelslist)
            col_annotation_widgets_top.append(labelslist)

            # Bottom attr annotations
            labelslist = GraphicsSimpleTextList(
                labels, parent=widget, orientation=Qt.Horizontal)
            labelslist.setAlignment(Qt.AlignTop | Qt.AlignHCenter)
            labelslist.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Fixed)

            grid.addItem(labelslist, BottomLabelsRow, Col0 + j)
            col_annotation_widgets.append(labelslist)
            col_annotation_widgets_bottom.append(labelslist)

        legend = GradientLegendWidget(
            parts.levels[0], parts.levels[1],
            parent=widget)

        legend.set_color_table(palette)
        legend.setMinimumSize(QSizeF(100, 20))
        legend.setVisible(self.legend)

        grid.addItem(legend, LegendRow, Col0)

        self.heatmap_scene.widget = widget
        self.heatmap_widget_grid = heatmap_widgets
        self.selection_manager.set_heatmap_widgets(heatmap_widgets)

        self.row_annotation_widgets = row_annotation_widgets
        self.col_annotation_widgets = col_annotation_widgets
        self.col_annotation_widgets_top = col_annotation_widgets_top
        self.col_annotation_widgets_bottom = col_annotation_widgets_bottom
        self.col_dendrograms = column_dendrograms
        self.row_dendrograms = row_dendrograms

        self.update_annotations()
        self.update_column_annotations()

        self.__update_size_constraints()

    def __update_size_constraints(self):
        if self.heatmap_scene.widget is not None:
            mode = Qt.KeepAspectRatio if self.keep_aspect \
                   else Qt.IgnoreAspectRatio
            size = QSizeF(self.sceneView.viewport().size())
            widget = self.heatmap_scene.widget
            layout = widget.layout()
            if mode == Qt.IgnoreAspectRatio:
                # Reset the row height constraints ...
                for i, hm_row in enumerate(self.heatmap_widget_grid):
                    layout.setRowMaximumHeight(3 + i * 2 + 1, np.finfo(np.float32).max)
                    layout.setRowPreferredHeight(3 + i * 2 + 1, 0)
                # ... and resize to match the viewport, taking the minimum size
                # into account
                minsize = widget.minimumSize()
                size = size.expandedTo(minsize)
                preferred = widget.effectiveSizeHint(Qt.PreferredSize)
                widget.resize(preferred.boundedTo(size))
            else:
                # First set/update the widget's width (the layout will
                # distribute the available width to heatmap widgets in
                # the grid)
                minsize = widget.minimumSize()
                preferred = widget.effectiveSizeHint(Qt.PreferredSize)

                if preferred.width() < size.expandedTo(minsize).width():
                    size = preferred

                widget.resize(size.expandedTo(minsize).width(),
                              widget.size().height())
                # calculate and set the heatmap row's heights based on
                # the width
                for i, hm_row in enumerate(self.heatmap_widget_grid):
                    heights = []
                    for hm in hm_row:
                        hm_size = QSizeF(hm.heatmap_item.pixmap().size())
                        hm_size = scaled(
                            hm_size, QSizeF(hm.size().width(), -1),
                            Qt.KeepAspectRatioByExpanding)

                        heights.append(hm_size.height())
                    layout.setRowMaximumHeight(3 + i * 2 + 1, max(heights))
                    layout.setRowPreferredHeight(3 + i * 2 + 1, max(heights))

                # set/update the widget's height
                constraint = QSizeF(size.width(), -1)
                sh = widget.effectiveSizeHint(Qt.PreferredSize, constraint)
                minsize = widget.effectiveSizeHint(Qt.MinimumSize, constraint)
                sh = sh.expandedTo(minsize).expandedTo(widget.minimumSize())

#                 print("Resize 2", sh)
#                 print("  old:", widget.size().width(), widget.size().height())
#                 print("  new:", widget.size().width(), sh.height())

                widget.resize(sh)
#                 print("Did resize")
            self.__fixup_grid_layout()

    def __fixup_grid_layout(self):
        self.__update_margins()
        rect = self.scene.widget.geometry()
        self.heatmap_scene.setSceneRect(rect)
        self.__update_selection_geometry()

    def __aspect_mode_changed(self):
        self.__update_size_constraints()

    def eventFilter(self, reciever, event):
        if reciever is self.sceneView.viewport() and \
                event.type() == QEvent.Resize:
            self.__update_size_constraints()

        return super().eventFilter(reciever, event)

    def __update_margins(self):
        """
        Update horizontal dendrogram and text list widgets margins to
        include the space for average stripe.
        """
        def offset(hm):
            if hm.show_averages:
                return hm.averages_item.size().width()
            else:
                return 0

        hm_row = self.heatmap_widget_grid[0]
        dendrogram_col = self.col_dendrograms

        col_annot = zip(self.col_annotation_widgets_top,
                        self.col_annotation_widgets_bottom)

        for hm, annot, dendrogram in zip(hm_row, col_annot, dendrogram_col):
            left_offset = offset(hm)
            if dendrogram is not None:
                _, top, right, bottom = dendrogram.getContentsMargins()
                dendrogram.setContentsMargins(
                    left_offset, top, right, bottom)

            _, top, right, bottom = annot[0].getContentsMargins()
            annot[0].setContentsMargins(left_offset, top, right, bottom)
            _, top, right, bottom = annot[1].getContentsMargins()
            annot[1].setContentsMargins(left_offset, top, right, bottom)

    def __update_clustering_enable_state(self, data):
        def enable(item, state):
            """Set QStandardItem's enabled state to `state`."""
            flags = item.flags()
            if state:
                item.setFlags(flags | Qt.ItemIsEnabled)
            else:
                item.setFlags(flags & ~Qt.ItemIsEnabled)

        if data is not None:
            N = len(data)
            M = len(data.domain.attributes)
        else:
            N = M = 0

        rco_enabled = N <= OWHeatMap._MaxOrderedClustering
        cco_enabled = M <= OWHeatMap._MaxOrderedClustering

        row_clust_msg = ""
        col_clust_msg = ""

        if not rco_enabled and self.row_clustering:
            self.row_clustering = False
            row_clust_msg = "Row clustering was disabled due to the " \
                            "input matrix being to big"

        if not cco_enabled and self.col_clustering:
            self.col_clustering = False
            col_clust_msg = "Column clustering was disabled due to " \
                            "the input matrix being to big"

        self.Information.row_clust.clear()
        self.Information.col_clust.clear()
        if row_clust_msg:
            self.Information.row_clust(row_clust_msg)
        if col_clust_msg:
            self.Information.col_clust(col_clust_msg)

        # Disable/enable the checkboxes for the clustering methods
        self.row_check.setEnabled(rco_enabled)
        self.col_check.setEnabled(cco_enabled)

    def heatmap_widgets(self):
        """Iterate over heatmap widgets.
        """
        for item in self.heatmap_scene.items():
            if isinstance(item, GraphicsHeatmapWidget):
                yield item

    def label_widgets(self):
        """Iterate over GraphicsSimpleTextList widgets.
        """
        for item in self.heatmap_scene.items():
            if isinstance(item, GraphicsSimpleTextList):
                yield item

    def dendrogram_widgets(self):
        """Iterate over dendrogram widgets
        """
        for item in self.heatmap_scene.items():
            if isinstance(item, DendrogramWidget):
                yield item

    def legend_widgets(self):
        for item in self.heatmap_scene.items():
            if isinstance(item, GradientLegendWidget):
                yield item

    def update_averages_stripe(self):
        """Update the visibility of the averages stripe.
        """
        if self.effective_data is not None:
            for widget in self.heatmap_widgets():
                widget.set_show_averages(self.averages)
                widget.layout().activate()

            self.scene.widget.layout().activate()
            self.__fixup_grid_layout()

    def update_grid_spacing(self):
        """Update layout spacing.
        """
        if self.scene.widget:
            layout = self.scene.widget.layout()
            layout.setSpacing(self.SpaceX)
            self.__fixup_grid_layout()

    def update_lowslider(self):
        low, high = self.controls.threshold_low, self.controls.threshold_high
        if low.value() >= high.value():
            low.setSliderPosition(high.value() - 1)
        self.update_color_schema()

    def update_highslider(self):
        low, high = self.controls.threshold_low, self.controls.threshold_high
        if low.value() >= high.value():
            high.setSliderPosition(low.value() + 1)
        self.update_color_schema()

    def update_color_schema(self):
        palette = self.color_palette()
        for heatmap in self.heatmap_widgets():
            heatmap.set_color_table(palette)

        for legend in self.legend_widgets():
            legend.set_color_table(palette)

    def update_sorting_examples(self):
        self.update_heatmaps()

    def update_clustering_examples(self):
        self.update_heatmaps()

    def update_legend(self):
        for item in self.heatmap_scene.items():
            if isinstance(item, GradientLegendWidget):
                item.setVisible(self.legend)

    def update_annotations(self):
        if self.input_data is not None:
            if self.annotation_vars:
                var = self.annotation_vars[self.annotation_index]
                if var == '(None)':
                    var = None
            else:
                var = None

            show = var is not None
            if show:
                annot_col, _ = self.input_data.get_column_view(var)
            else:
                annot_col = None

            if self.merge_kmeans and self.kmeans_model is not None:
                merge_indices = self.merge_indices
            else:
                merge_indices = None

            for labelslist in self.row_annotation_widgets:
                labelslist.setVisible(bool(show))
                if show:
                    indices = labelslist._indices
                    if merge_indices is not None:
                        join = lambda values: (
                            join_ellided(", ", 42, values, " ({} more)")
                        )
                        # collect all original labels for every merged row
                        values = [annot_col[merge_indices[i]] for i in indices]
                        labels = [join(list(map(var.str_val, vals)))
                                  for vals in values]
                    else:
                        data = annot_col[indices]
                        labels = [var.str_val(val) for val in data]

                    labelslist.set_labels(labels)

    def update_column_annotations(self):
        if self.data is not None:
            show_top = self.column_label_pos & OWHeatMap.PositionTop
            show_bottom = self.column_label_pos & OWHeatMap.PositionBottom

            for labelslist in self.col_annotation_widgets_top:
                labelslist.setVisible(show_top)

            TopLabelsRow = 2
            Row0 = 3
            BottomLabelsRow = Row0 + 2 * len(self.heatmapparts.rows)

            layout = self.heatmap_scene.widget.layout()
            layout.setRowMaximumHeight(TopLabelsRow, -1 if show_top else 0)
            layout.setRowSpacing(TopLabelsRow, -1 if show_top else 0)

            for labelslist in self.col_annotation_widgets_bottom:
                labelslist.setVisible(show_bottom)

            layout.setRowMaximumHeight(BottomLabelsRow, -1 if show_top else 0)

            self.__fixup_grid_layout()

    def __select_by_cluster(self, item, dendrogramindex):
        # User clicked on a dendrogram node.
        # Select all rows corresponding to the cluster item.
        node = item.node
        try:
            hm = self.heatmap_widget_grid[dendrogramindex][0]
        except IndexError:
            pass
        else:
            key = QApplication.keyboardModifiers()
            clear = not (key & ((Qt.ControlModifier | Qt.ShiftModifier |
                                 Qt.AltModifier)))
            remove = (key & (Qt.ControlModifier | Qt.AltModifier))
            append = (key & Qt.ControlModifier)
            self.selection_manager.selection_add(
                node.value.first, node.value.last - 1, hm,
                clear=clear, remove=remove, append=append)

    def __update_selection_geometry(self):
        for item in self.selection_rects:
            item.setParentItem(None)
            self.heatmap_scene.removeItem(item)

        self.selection_rects = []
        self.selection_manager.update_selection_rects()
        rects = self.selection_manager.selection_rects
        for rect in rects:
            item = QGraphicsRectItem(rect, None)
            pen = QPen(Qt.black, 2)
            pen.setCosmetic(True)
            item.setPen(pen)
            self.heatmap_scene.addItem(item)
            self.selection_rects.append(item)

    def on_selection_finished(self):
        self.selected_rows = self.selection_manager.selections
        self.commit()

    def commit(self):
        data = None
        indices = None
        if self.merge_kmeans:
            merge_indices = self.merge_indices
        else:
            merge_indices = None

        if self.input_data is not None and self.selected_rows:
            sortind = np.hstack([labels._indices
                                 for labels in self.row_annotation_widgets])
            indices = sortind[self.selected_rows]

            if merge_indices is not None:
                # expand merged indices
                indices = np.hstack([merge_indices[i] for i in indices])

            data = self.input_data[indices]

        self.send("Selected Data", data)
        self.send(ANNOTATED_DATA_SIGNAL_NAME,
                  create_annotated_table(self.input_data, indices))

    def onDeleteWidget(self):
        self.clear()
        super().onDeleteWidget()

    def send_report(self):
        self.report_items((
            ("Columns:", "Clustering" if self.col_clustering else "No sorting"),
            ("Rows:", "Clustering" if self.row_clustering else "No sorting"),
            ("Row annotation",
             self.annotation_index > 0 and
             self.annotation_vars[self.annotation_index])
        ))
        self.report_plot()


class GraphicsWidget(QGraphicsWidget):
    """A graphics widget which can notify on relayout events.
    """
    #: The widget's layout has activated (i.e. did a relayout
    #: of the widget's contents)
    layoutDidActivate = Signal()

    def event(self, event):
        rval = super().event(event)
        if event.type() == QEvent.LayoutRequest and self.layout() is not None:
            self.layoutDidActivate.emit()
        return rval

QWIDGETSIZE_MAX = 16777215


def scaled(size, constraint, mode=Qt.KeepAspectRatio):
    if constraint.width() < 0 and constraint.height() < 0:
        return size

    size, constraint = QSizeF(size), QSizeF(constraint)
    if mode == Qt.IgnoreAspectRatio:
        if constraint.width() >= 0:
            size.setWidth(constraint.width())
        if constraint.height() >= 0:
            size.setHeight(constraint.height())
    elif mode == Qt.KeepAspectRatio:
        if constraint.width() < 0:
            constraint.setWidth(QWIDGETSIZE_MAX)
        if constraint.height() < 0:
            constraint.setHeight(QWIDGETSIZE_MAX)
        size.scale(constraint, mode)
    elif mode == Qt.KeepAspectRatioByExpanding:
        if constraint.width() < 0:
            constraint.setWidth(0)
        if constraint.height() < 0:
            constraint.setHeight(0)
        size.scale(constraint, mode)
    return size


class GraphicsPixmapWidget(QGraphicsWidget):
    def __init__(self, parent=None, pixmap=None, scaleContents=False,
                 aspectMode=Qt.KeepAspectRatio, **kwargs):
        super().__init__(parent)
        self.setContentsMargins(0, 0, 0, 0)
        self.__scaleContents = scaleContents
        self.__aspectMode = aspectMode

        self.__pixmap = pixmap or QPixmap()
        self.__item = QGraphicsPixmapItem(self.__pixmap, self)
        self.__updateScale()

    def setPixmap(self, pixmap):
        self.prepareGeometryChange()
        self.__pixmap = pixmap or QPixmap()
        self.__item.setPixmap(self.__pixmap)
        self.updateGeometry()

    def pixmap(self):
        return self.__pixmap

    def setAspectRatioMode(self, mode):
        if self.__aspectMode != mode:
            self.__aspectMode = mode

    def aspectRatioMode(self):
        return self.__aspectMode

    def setScaleContents(self, scale):
        if self.__scaleContents != scale:
            self.__scaleContents = bool(scale)
            self.updateGeometry()
            self.__updateScale()

    def scaleContents(self):
        return self.__scaleContents

    def sizeHint(self, which, constraint=QSizeF()):
        if which == Qt.PreferredSize:
            sh = QSizeF(self.__pixmap.size())
            if self.__scaleContents:
                sh = scaled(sh, constraint, self.__aspectMode)
            return sh
        elif which == Qt.MinimumSize:
            if self.__scaleContents:
                return QSizeF(0, 0)
            else:
                return QSizeF(self.__pixmap.size())
        elif which == Qt.MaximumSize:
            if self.__scaleContents:
                return QSizeF()
            else:
                return QSizeF(self.__pixmap.size())
        else:
            # Qt.MinimumDescent
            return QSizeF()

    def setGeometry(self, rect):
        super().setGeometry(rect)
        crect = self.contentsRect()
        self.__item.setPos(crect.topLeft())
        self.__updateScale()

    def __updateScale(self):
        if self.__pixmap.isNull():
            return
        pxsize = QSizeF(self.__pixmap.size())
        crect = self.contentsRect()
        self.__item.setPos(crect.topLeft())

        if self.__scaleContents:
            csize = scaled(pxsize, crect.size(), self.__aspectMode)
        else:
            csize = pxsize

        xscale = csize.width() / pxsize.width()
        yscale = csize.height() / pxsize.height()

        t = QTransform().scale(xscale, yscale)
        self.__item.setTransform(t)

    def pixmapTransform(self):
        return QTransform(self.__item.transform())


class GraphicsHeatmapWidget(QGraphicsWidget):
    def __init__(self, parent=None, data=None, **kwargs):
        super().__init__(parent, **kwargs)
        self.setAcceptHoverEvents(True)

        self.__levels = None
        self.__colortable = None
        self.__data = data

        self.__pixmap = QPixmap()
        self.__avgpixmap = QPixmap()

        layout = QGraphicsLinearLayout(Qt.Horizontal)
        layout.setContentsMargins(0, 0, 0, 0)
        self.heatmap_item = GraphicsPixmapWidget(
            self, scaleContents=True, aspectMode=Qt.IgnoreAspectRatio)

        self.averages_item = GraphicsPixmapWidget(
            self, scaleContents=True, aspectMode=Qt.IgnoreAspectRatio)

        layout.addItem(self.averages_item)
        layout.addItem(self.heatmap_item)
        layout.setItemSpacing(0, 2)

        self.setLayout(layout)

        self.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)

        self.show_averages = True

        self.set_heatmap_data(data)

    def clear(self):
        """Clear/reset the widget."""
        self.__data = None
        self.__pixmap = None
        self.__avgpixmap = None

        self.heatmap_item.setPixmap(QPixmap())
        self.averages_item.setPixmap(QPixmap())
        self.show_averages = True
        self.updateGeometry()
        self.layout().invalidate()

    def set_heatmap(self, heatmap):
        """Set the heatmap data for display.
        """
        self.clear()

        self.set_heatmap_data(heatmap)
        self.update()

    def set_heatmap_data(self, data):
        """Set the heatmap data for display."""
        if self.__data is not data:
            self.clear()
            self.__data = data
            self._update_pixmap()
            self.update()

    def heatmap_data(self):
        if self.__data is not None:
            v = self.__data.view()
            v.flags.writeable = False
            return v
        else:
            return None

    def set_levels(self, levels):
        if levels != self.__levels:
            self.__levels = levels
            self._update_pixmap()
            self.update()

    def set_show_averages(self, show):
        if self.show_averages != show:
            self.show_averages = show
            self.averages_item.setVisible(show)
            self.averages_item.setMaximumWidth(-1 if show else 0)
            self.layout().invalidate()
            self.update()

    def set_color_table(self, table):
        self.__colortable = table
        self._update_pixmap()
        self.update()

    def _update_pixmap(self):
        """
        Update the pixmap if its construction arguments changed.
        """
        if self.__data is not None:
            if self.__colortable is not None:
                lut = self.__colortable
            else:
                lut = None
            argb, _ = pg.makeARGB(
                self.__data, lut=lut, levels=self.__levels, scale=250)
            argb[np.isnan(self.__data)] = (100, 100, 100, 255)

            qimage = pg.makeQImage(argb, transpose=False)
            self.__pixmap = QPixmap.fromImage(qimage)
            avg = np.nanmean(self.__data, axis=1, keepdims=True)
            argb, _ = pg.makeARGB(
                avg, lut=lut, levels=self.__levels, scale=250)
            qimage = pg.makeQImage(argb, transpose=False)
            self.__avgpixmap = QPixmap.fromImage(qimage)
        else:
            self.__pixmap = QPixmap()
            self.__avgpixmap = QPixmap()

        self.heatmap_item.setPixmap(self.__pixmap)
        self.averages_item.setPixmap(self.__avgpixmap)
        hmsize = QSizeF(self.__pixmap.size())
        avsize = QSizeF(self.__avgpixmap.size())

        self.heatmap_item.setMinimumSize(hmsize)
        self.averages_item.setMinimumSize(avsize)
        self.heatmap_item.setPreferredSize(hmsize * 10)
        self.averages_item.setPreferredSize(avsize * 10)
        self.layout().invalidate()

    def cell_at(self, pos):
        """Return the cell row, column from `pos` in local coordinates.
        """
        if self.__pixmap.isNull() or not (
                self.heatmap_item.geometry().contains(pos) or
                self.averages_item.geometry().contains(pos)):
            return (-1, -1)

        if self.heatmap_item.geometry().contains(pos):
            item_clicked = self.heatmap_item
        elif self.averages_item.geometry().contains(pos):
            item_clicked = self.averages_item
        pos = self.mapToItem(item_clicked, pos)
        size = self.heatmap_item.size()

        x, y = pos.x(), pos.y()

        N, M = self.__data.shape
        fx = x / size.width()
        fy = y / size.height()
        i = min(int(math.floor(fy * N)), N - 1)
        j = min(int(math.floor(fx * M)), M - 1)
        return i, j

    def cell_rect(self, row, column):
        """Return a rectangle in local coordinates containing the cell
        at `row` and `column`.
        """
        size = self.__pixmap.size()
        if not (0 <= column < size.width() or 0 <= row < size.height()):
            return QRectF()

        topleft = QPointF(column, row)
        bottomright = QPointF(column + 1, row + 1)
        t = self.heatmap_item.pixmapTransform()
        rect = t.mapRect(QRectF(topleft, bottomright))
        rect.translated(self.heatmap_item.pos())
        return rect

    def row_rect(self, row):
        """
        Return a QRectF in local coordinates containing the entire row.
        """
        rect = self.cell_rect(row, 0)
        rect.setLeft(0)
        rect.setRight(self.size().width())
        return rect

    def cell_tool_tip(self, row, column):
        return "{}, {}: {:g}".format(row, column, self.__data[row, column])

    def hoverMoveEvent(self, event):
        pos = event.pos()
        row, column = self.cell_at(pos)
        if row != -1:
            tooltip = self.cell_tool_tip(row, column)
            # TODO: Move/delegate to (Scene) helpEvent
            self.setToolTip(tooltip)
        return super().hoverMoveEvent(event)


class HeatmapScene(QGraphicsScene):
    """A Graphics Scene with heatmap widgets."""
    def __init__(self, parent=None):
        QGraphicsScene.__init__(self, parent)
        self.selection_manager = HeatmapSelectionManager()
        self.__selecting = False

    def set_selection_manager(self, manager):
        self.selection_manager = manager

    def _items(self, pos=None, cls=object):
        if pos is not None:
            items = self.items(QRectF(pos, QSizeF(3, 3)).translated(-1.5, -1.5))
        else:
            items = self.items()

        for item in items:
            if isinstance(item, cls):
                yield item

    def heatmap_at_pos(self, pos):
        items = list(self._items(pos, GraphicsHeatmapWidget))
        if items:
            return items[0]
        else:
            return None

    def heatmap_widgets(self):
        return self._items(None, GraphicsHeatmapWidget)

    def select_from_dendrogram(self, dendrogram, key):
        """Select all heatmap rows which belong to the dendrogram.
        """
        dendrogram_widget = dendrogram.parentWidget()
        anchors = list(dendrogram_widget.leaf_anchors())
        cluster = dendrogram.cluster
        start, end = anchors[cluster.first], anchors[cluster.last - 1]
        start, end = dendrogram_widget.mapToScene(start), dendrogram_widget.mapToScene(end)
        # Find a heatmap widget containing start and end y coordinates.

        heatmap = None
        for hm in self.heatmap_widgets():
            b_rect = hm.sceneBoundingRect()
            if b_rect.contains(QPointF(b_rect.center().x(), start.y())):
                heatmap = hm
                break

        if dendrogram:
            b_rect = heatmap.boundingRect()
            start, end = heatmap.mapFromScene(start), heatmap.mapFromScene(end)
            start, _ = heatmap.cell_at(QPointF(b_rect.center().x(), start.y()))
            end, _ = heatmap.cell_at(QPointF(b_rect.center().x(), end.y()))
            clear = not (key & ((Qt.ControlModifier | Qt.ShiftModifier |
                                 Qt.AltModifier)))
            remove = (key & (Qt.ControlModifier | Qt.AltModifier))
            append = (key & Qt.ControlModifier)
            self.selection_manager.selection_add(
                start, end, heatmap, clear=clear, remove=remove, append=append)
        return

    def mousePressEvent(self, event):
        pos = event.scenePos()
        heatmap = self.heatmap_at_pos(pos)
        if heatmap and event.button() & Qt.LeftButton:
            row, _ = heatmap.cell_at(heatmap.mapFromScene(pos))
            if row != -1:
                self.selection_manager.selection_start(heatmap, event)
                self.__selecting = True
        return QGraphicsScene.mousePressEvent(self, event)

    def mouseMoveEvent(self, event):
        pos = event.scenePos()
        heatmap = self.heatmap_at_pos(pos)
        if heatmap and event.buttons() & Qt.LeftButton and self.__selecting:
            row, _ = heatmap.cell_at(heatmap.mapFromScene(pos))
            if row != -1:
                self.selection_manager.selection_update(heatmap, event)
        return QGraphicsScene.mouseMoveEvent(self, event)

    def mouseReleaseEvent(self, event):
        pos = event.scenePos()
        heatmap = self.heatmap_at_pos(pos)
        if heatmap and event.button() == Qt.LeftButton and self.__selecting:
            row, _ = heatmap.cell_at(heatmap.mapFromScene(pos))
            self.selection_manager.selection_finish(heatmap, event)

        if event.button() == Qt.LeftButton and self.__selecting:
            self.__selecting = False

        return QGraphicsScene.mouseReleaseEvent(self, event)

    def mouseDoubleClickEvent(self, event):
        return QGraphicsScene.mouseDoubleClickEvent(self, event)


class GraphicsSimpleTextLayoutItem(QGraphicsLayoutItem):
    """ A Graphics layout item wrapping a QGraphicsSimpleTextItem alowing it
    to be managed by a layout.

    """
    def __init__(self, text_item, orientation=Qt.Horizontal, parent=None):
        super().__init__(parent)
        self.orientation = orientation
        self.text_item = text_item
        if orientation == Qt.Vertical:
            self.text_item.rotate(-90)
            self.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Fixed)
        else:
            self.setSizePolicy(QSizePolicy.Fixed, QSizePolicy.Expanding)

    def setGeometry(self, rect):
        super().setGeometry(rect)
        if self.orientation == Qt.Horizontal:
            self.text_item.setPos(rect.topLeft())
        else:
            self.text_item.setPos(rect.bottomLeft())

    def sizeHint(self, which, constraint=QSizeF()):
        if which in [Qt.PreferredSize]:
            size = self.text_item.boundingRect().size()
            if self.orientation == Qt.Horizontal:
                return size
            else:
                return QSizeF(size.height(), size.width())
        else:
            return QSizeF()

    def updateGeometry(self):
        super().updateGeometry()
        parent = self.parentLayoutItem()
        if parent.isLayout():
            parent.updateGeometry()

    def setFont(self, font):
        self.text_item.setFont(font)
        self.updateGeometry()

    def setText(self, text):
        self.text_item.setText(text)
        self.updateGeometry()


class GraphicsSimpleTextList(QGraphicsWidget):
    """A simple text list widget."""
    def __init__(self, labels=[], orientation=Qt.Vertical, parent=None):
        super().__init__(parent)
        self.label_items = []
        self.orientation = orientation
        self.alignment = Qt.AlignCenter
        self.__resize_in_progress = False

        layout = QGraphicsLinearLayout(orientation)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.setSpacing(0)
        self.setLayout(layout)
        self.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)
        self.set_labels(labels)

    def clear(self):
        """Remove all text items."""
        layout = self.layout()
        for i in reversed(range(layout.count())):
            item = layout.itemAt(i)
            item.text_item.setParentItem(None)
            if self.scene():
                self.scene().removeItem(item.text_item)
            layout.removeAt(i)

        self.label_items = []
#         self.updateGeometry()

    def set_labels(self, labels):
        """Set the text labels to show in the widget.
        """
        self.clear()
        orientation = Qt.Horizontal if self.orientation == Qt.Vertical else Qt.Vertical
        for text in labels:
            item = QGraphicsSimpleTextItem(text, self)
            item.setFont(self.font())
            item.setToolTip(text)
            item = GraphicsSimpleTextLayoutItem(item, orientation, parent=self)
            self.layout().addItem(item)
            self.layout().setAlignment(item, self.alignment)
            self.label_items.append(item)

    def setAlignment(self, alignment):
        """Set alignment of text items in the widget
        """
        self.alignment = alignment
        layout = self.layout()
        for i in range(layout.count()):
            layout.setAlignment(layout.itemAt(i), alignment)

    def sizeHint(self, which, constraint=QRectF()):
        if not self.isVisible():
            return QSizeF(0, 0)
        elif which == Qt.PreferredSize:
            fm = QFontMetrics(QApplication.instance().font())
            brects = [fm.boundingRect(item.text_item.text())
                      for item in self.label_items]
            spacing = self.layout().spacing()
            height = sum((r.height() + spacing for r in brects), 0)
            width = max((r.width() for r in brects), default=0)

            if self.orientation == Qt.Vertical:
                return QSizeF(width, height)
            else:
                return QSizeF(height, width)
        else:
            return super().sizeHint(which, constraint)

    def setVisible(self, visible):
        super().setVisible(visible)
        self.updateGeometry()

    def resizeEvent(self, event):
        super().resizeEvent(event)
        self.__resize_in_progress = True
        self._updateFontSize()
        self.__resize_in_progress = False

    def changeEvent(self, event):
        super().changeEvent(event)
        if event.type() == QEvent.FontChange:
            font = self.font()
            for item in self.label_items:
                item.setFont(font)

            if not self.__resize_in_progress:
                self.updateGeometry()
                self.layout().invalidate()
                self.layout().activate()

    def _updateFontSize(self):
        crect = self.contentsRect()
        if self.orientation == Qt.Vertical:
            h = crect.height()
        else:
            h = crect.width()
        n = len(self.label_items)
        if n == 0:
            return

        if self.scene() is not None:
            maxfontsize = self.scene().font().pointSize()
        else:
            maxfontsize = QApplication.instance().font().pointSize()

        lineheight = max(1, h / n)
        fontsize = min(self._pointSize(lineheight), maxfontsize)

        font = self.font()
        font.setPointSize(fontsize)
        self.setFont(font)

    def _pointSize(self, height):
        font = self.font()
        font.setPointSize(height)
        fix = 0
        while QFontMetrics(font).lineSpacing() > height and height - fix > 1:
            fix += 1
            font.setPointSize(height - fix)
        return height - fix


class GradientLegendWidget(QGraphicsWidget):
    def __init__(self, low, high, parent=None):
        super().__init__(parent)
        self.low = low
        self.high = high
        self.color_table = None

        layout = QGraphicsLinearLayout(Qt.Vertical)
        self.setLayout(layout)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.setSpacing(1)

        layout_labels = QGraphicsLinearLayout(Qt.Horizontal)
        layout.addItem(layout_labels)
        layout_labels.setContentsMargins(0, 0, 0, 0)
        label_lo = QGraphicsSimpleTextItem("%.2f" % low, self)
        label_hi = QGraphicsSimpleTextItem("%.2f" % high, self)
        self.item_low = GraphicsSimpleTextLayoutItem(label_lo, parent=self)
        self.item_high = GraphicsSimpleTextLayoutItem(label_hi, parent=self)

        layout_labels.addItem(self.item_low)
        layout_labels.addStretch(10)
        layout_labels.addItem(self.item_high)

        self.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Fixed)
        self.__pixitem = GraphicsPixmapWidget(parent=self, scaleContents=True,
                                              aspectMode=Qt.IgnoreAspectRatio)
        self.__pixitem.setMinimumHeight(12)
        layout.addItem(self.__pixitem)
        self.__update()

    def set_color_table(self, color_table):
        self.color_table = color_table
        self.__update()

    def __update(self):
        data = np.linspace(self.low, self.high, num=50, endpoint=True)
        data = data.reshape((1, -1))
        argb, _ = pg.makeARGB(data, lut=self.color_table,
                              levels=(self.low, self.high))
        qimg = pg.makeQImage(argb, transpose=False)
        self.__pixitem.setPixmap(QPixmap.fromImage(qimg))

        self.item_low.setText("%.2f" % self.low)
        self.item_high.setText("%.2f" % self.high)
        self.layout().invalidate()


class HeatmapSelectionManager(QObject):
    """Selection manager for heatmap rows
    """
    selection_changed = Signal()
    selection_finished = Signal()

    def __init__(self, parent=None):
        QObject.__init__(self, parent)
        self.selections = []
        self.selection_ranges = []
        self.selection_ranges_temp = []
        self.heatmap_widgets = []
        self.selection_rects = []
        self.heatmaps = []
        self._heatmap_ranges = {}
        self._start_row = 0

    def clear(self):
        self.remove_rows(self.selection)

    def set_heatmap_widgets(self, widgets):
        self.remove_rows(self.selections)
        self.heatmaps = list(zip(*widgets))

        # Compute row ranges for all heatmaps
        self._heatmap_ranges = {}
        start = end = 0

        for group in zip(*widgets):
            start = end = 0
            for heatmap in group:
                end += heatmap.heatmap_data().shape[0]
                self._heatmap_ranges[heatmap] = (start, end)
                start = end

    def select_rows(self, rows, heatmap=None, clear=True):
        """Add `rows` to selection. If `heatmap` is provided the rows
        are mapped from the local indices to global heatmap indices. If `clear`
        then remove previous rows.
        """
        if heatmap is not None:
            start, _ = self._heatmap_ranges[heatmap]
            rows = [start + r for r in rows]

        old_selection = list(self.selections)
        if clear:
            self.selections = rows
        else:
            self.selections = sorted(set(self.selections + rows))

        if self.selections != old_selection:
            self.update_selection_rects()
            self.selection_changed.emit()

    def remove_rows(self, rows):
        """Remove `rows` from the selection.
        """
        old_selection = list(self.selections)
        self.selections = sorted(set(self.selections) - set(rows))
        if old_selection != self.selections:
            self.update_selection_rects()
            self.selection_changed.emit()

    def combined_ranges(self, ranges):
        combined_ranges = set()
        for start, end in ranges:
            if start <= end:
                rng = range(start, end + 1)
            else:
                rng = range(start, end - 1, -1)
            combined_ranges.update(rng)
        return sorted(combined_ranges)

    def selection_start(self, heatmap_widget, event):
        """ Selection  started by `heatmap_widget` due to `event`.
        """
        pos = heatmap_widget.mapFromScene(event.scenePos())
        row, _ = heatmap_widget.cell_at(pos)

        start, _ = self._heatmap_ranges[heatmap_widget]
        row = start + row
        self._start_row = row
        range = (row, row)
        self.selection_ranges_temp = []
        if event.modifiers() & Qt.ControlModifier:
            self.selection_ranges_temp = self.selection_ranges
            self.selection_ranges = self.remove_range(
                self.selection_ranges, row, row, append=True)
        elif event.modifiers() & Qt.ShiftModifier:
            self.selection_ranges.append(range)
        elif event.modifiers() & Qt.AltModifier:
            self.selection_ranges = self.remove_range(
                self.selection_ranges, row, row, append=False)
        else:
            self.selection_ranges = [range]
        self.select_rows(self.combined_ranges(self.selection_ranges))

    def selection_update(self, heatmap_widget, event):
        """ Selection updated by `heatmap_widget due to `event` (mouse drag).
        """
        pos = heatmap_widget.mapFromScene(event.scenePos())
        row, _ = heatmap_widget.cell_at(pos)
        if row < 0:
            return

        start, _ = self._heatmap_ranges[heatmap_widget]
        row = start + row
        if event.modifiers() & Qt.ControlModifier:
            self.selection_ranges = self.remove_range(
                self.selection_ranges_temp, self._start_row, row, append=True)
        elif event.modifiers() & Qt.AltModifier:
            self.selection_ranges = self.remove_range(
                self.selection_ranges, self._start_row, row, append=False)
        else:
            if self.selection_ranges:
                self.selection_ranges[-1] = (self._start_row, row)
            else:
                self.selection_ranges = [(row, row)]

        self.select_rows(self.combined_ranges(self.selection_ranges))

    def selection_finish(self, heatmap_widget, event):
        """ Selection finished by `heatmap_widget due to `event`.
        """
        pos = heatmap_widget.mapFromScene(event.scenePos())
        row, _ = heatmap_widget.cell_at(pos)
        start, _ = self._heatmap_ranges[heatmap_widget]
        row = start + row
        if event.modifiers() & Qt.ControlModifier:
            pass
        elif event.modifiers() & Qt.AltModifier:
            self.selection_ranges = self.remove_range(
                self.selection_ranges, self._start_row, row, append=False)
        else:
            if len(self.selection_ranges) > 0:
                self.selection_ranges[-1] = (self._start_row, row)
        self.select_rows(self.combined_ranges(self.selection_ranges))
        self.selection_finished.emit()

    def selection_add(self, start, end, heatmap=None, clear=True,
                      remove=False, append=False):
        """ Add/remove a selection range from `start` to `end`.
        """
        if heatmap is not None:
            _start, _ = self._heatmap_ranges[heatmap]
            start = _start + start
            end = _start + end

        if clear:
            self.selection_ranges = []
        if remove:
            self.selection_ranges = self.remove_range(
                self.selection_ranges, start, end, append=append)
        else:
            self.selection_ranges.append((start, end))
        self.select_rows(self.combined_ranges(self.selection_ranges))
        self.selection_finished.emit()

    def remove_range(self, ranges, start, end, append=False):
        if start > end:
            start, end = end, start
        comb_ranges = [i for i in self.combined_ranges(ranges)
                       if i > end or i < start]
        if append:
            comb_ranges += [i for i in range(start, end + 1)
                            if i not in self.combined_ranges(ranges)]
            comb_ranges = sorted(comb_ranges)
        return self.combined_to_ranges(comb_ranges)

    def combined_to_ranges(self, comb_ranges):
        ranges = []
        if len(comb_ranges) > 0:
            i, start, end = 0, comb_ranges[0], comb_ranges[0]
            for val in comb_ranges[1:]:
                i += 1
                if start + i < val:
                    ranges.append((start, end))
                    i, start = 0, val
                end = val
            ranges.append((start, end))
        return ranges

    def update_selection_rects(self):
        """ Update the selection rects.
        """
        def continuous_ranges(selections):
            """ Group continuous ranges
            """
            selections = iter(selections)
            start = end = next(selections)
            try:
                while True:
                    new_end = next(selections)
                    if new_end > end + 1:
                        yield start, end
                        start = end = new_end
                    else:
                        end = new_end
            except StopIteration:
                yield start, end

        def group_selections(selections):
            """Group selections along with heatmaps.
            """
            rows2hm = self.rows_to_heatmaps()
            selections = iter(selections)
            try:
                start = end = next(selections)
            except StopIteration:
                return
            end_heatmaps = rows2hm[end]
            try:
                while True:
                    new_end = next(selections)
                    new_end_heatmaps = rows2hm[new_end]
                    if new_end > end + 1 or new_end_heatmaps != end_heatmaps:
                        yield start, end, end_heatmaps
                        start = end = new_end
                        end_heatmaps = new_end_heatmaps
                    else:
                        end = new_end

            except StopIteration:
                yield start, end, end_heatmaps

        def selection_rect(start, end, heatmaps):
            rect = QRectF()
            for heatmap in heatmaps:
                h_start, _ = self._heatmap_ranges[heatmap]
                rect |= heatmap.mapToScene(heatmap.row_rect(start - h_start)).boundingRect()
                rect |= heatmap.mapToScene(heatmap.row_rect(end - h_start)).boundingRect()
            return rect

        self.selection_rects = []
        for start, end, heatmaps in group_selections(self.selections):
            rect = selection_rect(start, end, heatmaps)
            self.selection_rects.append(rect)

    def rows_to_heatmaps(self):
        heatmap_groups = zip(*self.heatmaps)
        rows2hm = {}
        for heatmaps in heatmap_groups:
            hm = heatmaps[0]
            start, end = self._heatmap_ranges[hm]
            rows2hm.update(dict.fromkeys(range(start, end), heatmaps))
        return rows2hm


def join_ellided(sep, maxlen, values, ellidetemplate="..."):
    def generate(sep, ellidetemplate, values):
        count = len(values)
        length = 0
        parts = []
        for i, val in enumerate(values):
            ellide = ellidetemplate.format(count - i) if count - i > 1 else ""
            parts.append(val)
            length += len(val) + (len(sep) if parts else 0)
            yield i, itertools.islice(parts, i + 1), length, ellide

    best = None
    for i, parts, length, ellide in generate(sep, ellidetemplate, values):
        if length > maxlen:
            if best is None:
                best = sep.join(parts) + ellide
            return best
        fulllen = length + len(ellide)
        if fulllen < maxlen or best is None:
            best = sep.join(parts) + ellide
    else:
        return best


def test_main(argv=sys.argv):
    if len(argv) > 1:
        filename = argv[1]
    else:
        filename = "brown-selected"

    app = QApplication(argv)
    ow = OWHeatMap()

    ow.set_dataset(Table(filename))
    ow.handleNewSignals()
    ow.show()
    ow.raise_()
    app.exec_()
    ow.set_dataset(None)
    ow.handleNewSignals()
    ow.saveSettings()
    return 0

if __name__ == "__main__":
    sys.exit(test_main())
