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# daal4py SVD example for distributed memory systems; SPMD mode
# run like this:
#    mpirun -n 4 python ./svd_spmd.py

import daal4py as d4p
from numpy import loadtxt, allclose

def main():
    # Each process gets its own data
    infile = "./data/distributed/svd_{}.csv".format(d4p.my_procid()+1)

    # configure a SVD object
    algo = d4p.svd(distributed=True)
    
    # let's provide a file directly, not a table/array
    result1 = algo.compute(infile)

    # We can also load the data ourselfs and provide the numpy array
    data = loadtxt(infile, delimiter=',')
    result2 = algo.compute(data)

    # SVD result objects provide leftSingularMatrix, rightSingularMatrix and singularValues
    assert result1.leftSingularMatrix.shape == data.shape
    assert result1.singularValues.shape == (1, data.shape[1])
    assert result1.rightSingularMatrix.shape == (data.shape[1], data.shape[1])

    assert allclose(result1.leftSingularMatrix, result2.leftSingularMatrix, atol=1e-05)
    assert allclose(result1.rightSingularMatrix, result2.rightSingularMatrix, atol=1e-05)
    assert allclose(result1.singularValues, result2.singularValues, atol=1e-05)

    return data, result1


if __name__ == "__main__":
    # Initialize SPMD mode
    d4p.daalinit()
    (_, result) = main()
    # result is available on all processes - but we print only on root
    if d4p.my_procid() == 0:
        print("\nEach process has singularValues and rightSingularMatrix but only his part of leftSingularMatrix:\n")
        print(result)
        print('All looks good!')
    d4p.daalfini()
