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861 lines
26 KiB
Python
861 lines
26 KiB
Python
"""Functions to construct sparse matrices
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"""
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__docformat__ = "restructuredtext en"
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__all__ = ['spdiags', 'eye', 'identity', 'kron', 'kronsum',
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'hstack', 'vstack', 'bmat', 'rand', 'random', 'diags', 'block_diag']
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import numbers
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from functools import partial
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import numpy as np
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from scipy._lib._util import check_random_state, rng_integers
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from .sputils import upcast, get_index_dtype, isscalarlike
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from .csr import csr_matrix
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from .csc import csc_matrix
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from .bsr import bsr_matrix
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from .coo import coo_matrix
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from .dia import dia_matrix
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from .base import issparse
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def spdiags(data, diags, m, n, format=None):
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"""
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Return a sparse matrix from diagonals.
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Parameters
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----------
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data : array_like
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matrix diagonals stored row-wise
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diags : diagonals to set
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- k = 0 the main diagonal
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- k > 0 the k-th upper diagonal
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- k < 0 the k-th lower diagonal
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m, n : int
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shape of the result
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format : str, optional
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Format of the result. By default (format=None) an appropriate sparse
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matrix format is returned. This choice is subject to change.
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See Also
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--------
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diags : more convenient form of this function
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dia_matrix : the sparse DIAgonal format.
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Examples
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--------
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>>> from scipy.sparse import spdiags
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>>> data = np.array([[1, 2, 3, 4], [1, 2, 3, 4], [1, 2, 3, 4]])
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>>> diags = np.array([0, -1, 2])
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>>> spdiags(data, diags, 4, 4).toarray()
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array([[1, 0, 3, 0],
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[1, 2, 0, 4],
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[0, 2, 3, 0],
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[0, 0, 3, 4]])
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"""
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return dia_matrix((data, diags), shape=(m,n)).asformat(format)
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def diags(diagonals, offsets=0, shape=None, format=None, dtype=None):
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"""
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Construct a sparse matrix from diagonals.
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Parameters
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----------
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diagonals : sequence of array_like
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Sequence of arrays containing the matrix diagonals,
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corresponding to `offsets`.
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offsets : sequence of int or an int, optional
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Diagonals to set:
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- k = 0 the main diagonal (default)
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- k > 0 the kth upper diagonal
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- k < 0 the kth lower diagonal
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shape : tuple of int, optional
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Shape of the result. If omitted, a square matrix large enough
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to contain the diagonals is returned.
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format : {"dia", "csr", "csc", "lil", ...}, optional
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Matrix format of the result. By default (format=None) an
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appropriate sparse matrix format is returned. This choice is
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subject to change.
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dtype : dtype, optional
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Data type of the matrix.
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See Also
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--------
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spdiags : construct matrix from diagonals
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Notes
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-----
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This function differs from `spdiags` in the way it handles
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off-diagonals.
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The result from `diags` is the sparse equivalent of::
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np.diag(diagonals[0], offsets[0])
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+ ...
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+ np.diag(diagonals[k], offsets[k])
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Repeated diagonal offsets are disallowed.
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.. versionadded:: 0.11
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Examples
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--------
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>>> from scipy.sparse import diags
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>>> diagonals = [[1, 2, 3, 4], [1, 2, 3], [1, 2]]
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>>> diags(diagonals, [0, -1, 2]).toarray()
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array([[1, 0, 1, 0],
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[1, 2, 0, 2],
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[0, 2, 3, 0],
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[0, 0, 3, 4]])
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Broadcasting of scalars is supported (but shape needs to be
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specified):
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>>> diags([1, -2, 1], [-1, 0, 1], shape=(4, 4)).toarray()
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array([[-2., 1., 0., 0.],
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[ 1., -2., 1., 0.],
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[ 0., 1., -2., 1.],
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[ 0., 0., 1., -2.]])
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If only one diagonal is wanted (as in `numpy.diag`), the following
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works as well:
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>>> diags([1, 2, 3], 1).toarray()
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array([[ 0., 1., 0., 0.],
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[ 0., 0., 2., 0.],
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[ 0., 0., 0., 3.],
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[ 0., 0., 0., 0.]])
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"""
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# if offsets is not a sequence, assume that there's only one diagonal
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if isscalarlike(offsets):
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# now check that there's actually only one diagonal
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if len(diagonals) == 0 or isscalarlike(diagonals[0]):
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diagonals = [np.atleast_1d(diagonals)]
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else:
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raise ValueError("Different number of diagonals and offsets.")
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else:
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diagonals = list(map(np.atleast_1d, diagonals))
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offsets = np.atleast_1d(offsets)
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# Basic check
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if len(diagonals) != len(offsets):
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raise ValueError("Different number of diagonals and offsets.")
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# Determine shape, if omitted
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if shape is None:
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m = len(diagonals[0]) + abs(int(offsets[0]))
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shape = (m, m)
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# Determine data type, if omitted
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if dtype is None:
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dtype = np.common_type(*diagonals)
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# Construct data array
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m, n = shape
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M = max([min(m + offset, n - offset) + max(0, offset)
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for offset in offsets])
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M = max(0, M)
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data_arr = np.zeros((len(offsets), M), dtype=dtype)
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K = min(m, n)
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for j, diagonal in enumerate(diagonals):
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offset = offsets[j]
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k = max(0, offset)
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length = min(m + offset, n - offset, K)
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if length < 0:
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raise ValueError("Offset %d (index %d) out of bounds" % (offset, j))
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try:
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data_arr[j, k:k+length] = diagonal[...,:length]
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except ValueError as e:
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if len(diagonal) != length and len(diagonal) != 1:
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raise ValueError(
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"Diagonal length (index %d: %d at offset %d) does not "
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"agree with matrix size (%d, %d)." % (
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j, len(diagonal), offset, m, n)) from e
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raise
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return dia_matrix((data_arr, offsets), shape=(m, n)).asformat(format)
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def identity(n, dtype='d', format=None):
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"""Identity matrix in sparse format
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Returns an identity matrix with shape (n,n) using a given
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sparse format and dtype.
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Parameters
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----------
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n : int
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Shape of the identity matrix.
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dtype : dtype, optional
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Data type of the matrix
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format : str, optional
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Sparse format of the result, e.g., format="csr", etc.
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Examples
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--------
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>>> from scipy.sparse import identity
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>>> identity(3).toarray()
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array([[ 1., 0., 0.],
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[ 0., 1., 0.],
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[ 0., 0., 1.]])
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>>> identity(3, dtype='int8', format='dia')
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<3x3 sparse matrix of type '<class 'numpy.int8'>'
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with 3 stored elements (1 diagonals) in DIAgonal format>
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"""
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return eye(n, n, dtype=dtype, format=format)
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def eye(m, n=None, k=0, dtype=float, format=None):
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"""Sparse matrix with ones on diagonal
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Returns a sparse (m x n) matrix where the kth diagonal
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is all ones and everything else is zeros.
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Parameters
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----------
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m : int
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Number of rows in the matrix.
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n : int, optional
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Number of columns. Default: `m`.
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k : int, optional
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Diagonal to place ones on. Default: 0 (main diagonal).
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dtype : dtype, optional
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Data type of the matrix.
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format : str, optional
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Sparse format of the result, e.g., format="csr", etc.
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Examples
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--------
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>>> from scipy import sparse
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>>> sparse.eye(3).toarray()
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array([[ 1., 0., 0.],
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[ 0., 1., 0.],
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[ 0., 0., 1.]])
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>>> sparse.eye(3, dtype=np.int8)
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<3x3 sparse matrix of type '<class 'numpy.int8'>'
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with 3 stored elements (1 diagonals) in DIAgonal format>
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"""
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if n is None:
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n = m
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m,n = int(m),int(n)
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if m == n and k == 0:
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# fast branch for special formats
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if format in ['csr', 'csc']:
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idx_dtype = get_index_dtype(maxval=n)
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indptr = np.arange(n+1, dtype=idx_dtype)
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indices = np.arange(n, dtype=idx_dtype)
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data = np.ones(n, dtype=dtype)
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cls = {'csr': csr_matrix, 'csc': csc_matrix}[format]
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return cls((data,indices,indptr),(n,n))
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elif format == 'coo':
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idx_dtype = get_index_dtype(maxval=n)
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row = np.arange(n, dtype=idx_dtype)
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col = np.arange(n, dtype=idx_dtype)
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data = np.ones(n, dtype=dtype)
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return coo_matrix((data,(row,col)),(n,n))
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diags = np.ones((1, max(0, min(m + k, n))), dtype=dtype)
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return spdiags(diags, k, m, n).asformat(format)
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def kron(A, B, format=None):
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"""kronecker product of sparse matrices A and B
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Parameters
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----------
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A : sparse or dense matrix
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first matrix of the product
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B : sparse or dense matrix
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second matrix of the product
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format : str, optional
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format of the result (e.g. "csr")
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Returns
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-------
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kronecker product in a sparse matrix format
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Examples
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--------
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>>> from scipy import sparse
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>>> A = sparse.csr_matrix(np.array([[0, 2], [5, 0]]))
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>>> B = sparse.csr_matrix(np.array([[1, 2], [3, 4]]))
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>>> sparse.kron(A, B).toarray()
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array([[ 0, 0, 2, 4],
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[ 0, 0, 6, 8],
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[ 5, 10, 0, 0],
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[15, 20, 0, 0]])
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>>> sparse.kron(A, [[1, 2], [3, 4]]).toarray()
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array([[ 0, 0, 2, 4],
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[ 0, 0, 6, 8],
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[ 5, 10, 0, 0],
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[15, 20, 0, 0]])
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"""
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B = coo_matrix(B)
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if (format is None or format == "bsr") and 2*B.nnz >= B.shape[0] * B.shape[1]:
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# B is fairly dense, use BSR
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A = csr_matrix(A,copy=True)
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output_shape = (A.shape[0]*B.shape[0], A.shape[1]*B.shape[1])
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if A.nnz == 0 or B.nnz == 0:
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# kronecker product is the zero matrix
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return coo_matrix(output_shape).asformat(format)
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B = B.toarray()
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data = A.data.repeat(B.size).reshape(-1,B.shape[0],B.shape[1])
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data = data * B
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return bsr_matrix((data,A.indices,A.indptr), shape=output_shape)
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else:
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# use COO
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A = coo_matrix(A)
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output_shape = (A.shape[0]*B.shape[0], A.shape[1]*B.shape[1])
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if A.nnz == 0 or B.nnz == 0:
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# kronecker product is the zero matrix
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return coo_matrix(output_shape).asformat(format)
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# expand entries of a into blocks
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row = A.row.repeat(B.nnz)
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col = A.col.repeat(B.nnz)
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data = A.data.repeat(B.nnz)
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if max(A.shape[0]*B.shape[0], A.shape[1]*B.shape[1]) > np.iinfo('int32').max:
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row = row.astype(np.int64)
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col = col.astype(np.int64)
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row *= B.shape[0]
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col *= B.shape[1]
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# increment block indices
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row,col = row.reshape(-1,B.nnz),col.reshape(-1,B.nnz)
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row += B.row
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col += B.col
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row,col = row.reshape(-1),col.reshape(-1)
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# compute block entries
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data = data.reshape(-1,B.nnz) * B.data
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data = data.reshape(-1)
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return coo_matrix((data,(row,col)), shape=output_shape).asformat(format)
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def kronsum(A, B, format=None):
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"""kronecker sum of sparse matrices A and B
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Kronecker sum of two sparse matrices is a sum of two Kronecker
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products kron(I_n,A) + kron(B,I_m) where A has shape (m,m)
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and B has shape (n,n) and I_m and I_n are identity matrices
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of shape (m,m) and (n,n), respectively.
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Parameters
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----------
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A
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square matrix
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B
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square matrix
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format : str
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format of the result (e.g. "csr")
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Returns
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-------
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kronecker sum in a sparse matrix format
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Examples
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--------
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"""
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A = coo_matrix(A)
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B = coo_matrix(B)
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if A.shape[0] != A.shape[1]:
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raise ValueError('A is not square')
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if B.shape[0] != B.shape[1]:
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raise ValueError('B is not square')
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dtype = upcast(A.dtype, B.dtype)
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L = kron(eye(B.shape[0],dtype=dtype), A, format=format)
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R = kron(B, eye(A.shape[0],dtype=dtype), format=format)
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return (L+R).asformat(format) # since L + R is not always same format
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def _compressed_sparse_stack(blocks, axis):
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"""
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Stacking fast path for CSR/CSC matrices
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(i) vstack for CSR, (ii) hstack for CSC.
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"""
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other_axis = 1 if axis == 0 else 0
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data = np.concatenate([b.data for b in blocks])
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constant_dim = blocks[0].shape[other_axis]
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idx_dtype = get_index_dtype(arrays=[b.indptr for b in blocks],
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maxval=max(data.size, constant_dim))
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indices = np.empty(data.size, dtype=idx_dtype)
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indptr = np.empty(sum(b.shape[axis] for b in blocks) + 1, dtype=idx_dtype)
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last_indptr = idx_dtype(0)
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sum_dim = 0
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sum_indices = 0
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for b in blocks:
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if b.shape[other_axis] != constant_dim:
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raise ValueError('incompatible dimensions for axis %d' % other_axis)
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indices[sum_indices:sum_indices+b.indices.size] = b.indices
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sum_indices += b.indices.size
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idxs = slice(sum_dim, sum_dim + b.shape[axis])
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indptr[idxs] = b.indptr[:-1]
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indptr[idxs] += last_indptr
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sum_dim += b.shape[axis]
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last_indptr += b.indptr[-1]
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indptr[-1] = last_indptr
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if axis == 0:
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return csr_matrix((data, indices, indptr),
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shape=(sum_dim, constant_dim))
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else:
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return csc_matrix((data, indices, indptr),
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shape=(constant_dim, sum_dim))
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def hstack(blocks, format=None, dtype=None):
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"""
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Stack sparse matrices horizontally (column wise)
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Parameters
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----------
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blocks
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sequence of sparse matrices with compatible shapes
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format : str
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sparse format of the result (e.g., "csr")
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by default an appropriate sparse matrix format is returned.
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This choice is subject to change.
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dtype : dtype, optional
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The data-type of the output matrix. If not given, the dtype is
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determined from that of `blocks`.
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See Also
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--------
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vstack : stack sparse matrices vertically (row wise)
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Examples
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--------
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>>> from scipy.sparse import coo_matrix, hstack
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>>> A = coo_matrix([[1, 2], [3, 4]])
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>>> B = coo_matrix([[5], [6]])
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>>> hstack([A,B]).toarray()
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array([[1, 2, 5],
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[3, 4, 6]])
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"""
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return bmat([blocks], format=format, dtype=dtype)
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def vstack(blocks, format=None, dtype=None):
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"""
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Stack sparse matrices vertically (row wise)
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Parameters
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----------
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blocks
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sequence of sparse matrices with compatible shapes
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format : str, optional
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sparse format of the result (e.g., "csr")
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by default an appropriate sparse matrix format is returned.
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This choice is subject to change.
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dtype : dtype, optional
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The data-type of the output matrix. If not given, the dtype is
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determined from that of `blocks`.
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See Also
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--------
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hstack : stack sparse matrices horizontally (column wise)
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Examples
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--------
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>>> from scipy.sparse import coo_matrix, vstack
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>>> A = coo_matrix([[1, 2], [3, 4]])
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>>> B = coo_matrix([[5, 6]])
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>>> vstack([A, B]).toarray()
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array([[1, 2],
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[3, 4],
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[5, 6]])
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"""
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return bmat([[b] for b in blocks], format=format, dtype=dtype)
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def bmat(blocks, format=None, dtype=None):
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"""
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Build a sparse matrix from sparse sub-blocks
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Parameters
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----------
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blocks : array_like
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Grid of sparse matrices with compatible shapes.
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An entry of None implies an all-zero matrix.
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format : {'bsr', 'coo', 'csc', 'csr', 'dia', 'dok', 'lil'}, optional
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The sparse format of the result (e.g. "csr"). By default an
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appropriate sparse matrix format is returned.
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This choice is subject to change.
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dtype : dtype, optional
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The data-type of the output matrix. If not given, the dtype is
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determined from that of `blocks`.
|
|
|
|
Returns
|
|
-------
|
|
bmat : sparse matrix
|
|
|
|
See Also
|
|
--------
|
|
block_diag, diags
|
|
|
|
Examples
|
|
--------
|
|
>>> from scipy.sparse import coo_matrix, bmat
|
|
>>> A = coo_matrix([[1, 2], [3, 4]])
|
|
>>> B = coo_matrix([[5], [6]])
|
|
>>> C = coo_matrix([[7]])
|
|
>>> bmat([[A, B], [None, C]]).toarray()
|
|
array([[1, 2, 5],
|
|
[3, 4, 6],
|
|
[0, 0, 7]])
|
|
|
|
>>> bmat([[A, None], [None, C]]).toarray()
|
|
array([[1, 2, 0],
|
|
[3, 4, 0],
|
|
[0, 0, 7]])
|
|
|
|
"""
|
|
|
|
blocks = np.asarray(blocks, dtype='object')
|
|
|
|
if blocks.ndim != 2:
|
|
raise ValueError('blocks must be 2-D')
|
|
|
|
M,N = blocks.shape
|
|
|
|
# check for fast path cases
|
|
if (N == 1 and format in (None, 'csr') and all(isinstance(b, csr_matrix)
|
|
for b in blocks.flat)):
|
|
A = _compressed_sparse_stack(blocks[:,0], 0)
|
|
if dtype is not None:
|
|
A = A.astype(dtype)
|
|
return A
|
|
elif (M == 1 and format in (None, 'csc')
|
|
and all(isinstance(b, csc_matrix) for b in blocks.flat)):
|
|
A = _compressed_sparse_stack(blocks[0,:], 1)
|
|
if dtype is not None:
|
|
A = A.astype(dtype)
|
|
return A
|
|
|
|
block_mask = np.zeros(blocks.shape, dtype=bool)
|
|
brow_lengths = np.zeros(M, dtype=np.int64)
|
|
bcol_lengths = np.zeros(N, dtype=np.int64)
|
|
|
|
# convert everything to COO format
|
|
for i in range(M):
|
|
for j in range(N):
|
|
if blocks[i,j] is not None:
|
|
A = coo_matrix(blocks[i,j])
|
|
blocks[i,j] = A
|
|
block_mask[i,j] = True
|
|
|
|
if brow_lengths[i] == 0:
|
|
brow_lengths[i] = A.shape[0]
|
|
elif brow_lengths[i] != A.shape[0]:
|
|
msg = ('blocks[{i},:] has incompatible row dimensions. '
|
|
'Got blocks[{i},{j}].shape[0] == {got}, '
|
|
'expected {exp}.'.format(i=i, j=j,
|
|
exp=brow_lengths[i],
|
|
got=A.shape[0]))
|
|
raise ValueError(msg)
|
|
|
|
if bcol_lengths[j] == 0:
|
|
bcol_lengths[j] = A.shape[1]
|
|
elif bcol_lengths[j] != A.shape[1]:
|
|
msg = ('blocks[:,{j}] has incompatible row dimensions. '
|
|
'Got blocks[{i},{j}].shape[1] == {got}, '
|
|
'expected {exp}.'.format(i=i, j=j,
|
|
exp=bcol_lengths[j],
|
|
got=A.shape[1]))
|
|
raise ValueError(msg)
|
|
|
|
nnz = sum(block.nnz for block in blocks[block_mask])
|
|
if dtype is None:
|
|
all_dtypes = [blk.dtype for blk in blocks[block_mask]]
|
|
dtype = upcast(*all_dtypes) if all_dtypes else None
|
|
|
|
row_offsets = np.append(0, np.cumsum(brow_lengths))
|
|
col_offsets = np.append(0, np.cumsum(bcol_lengths))
|
|
|
|
shape = (row_offsets[-1], col_offsets[-1])
|
|
|
|
data = np.empty(nnz, dtype=dtype)
|
|
idx_dtype = get_index_dtype(maxval=max(shape))
|
|
row = np.empty(nnz, dtype=idx_dtype)
|
|
col = np.empty(nnz, dtype=idx_dtype)
|
|
|
|
nnz = 0
|
|
ii, jj = np.nonzero(block_mask)
|
|
for i, j in zip(ii, jj):
|
|
B = blocks[i, j]
|
|
idx = slice(nnz, nnz + B.nnz)
|
|
data[idx] = B.data
|
|
row[idx] = B.row + row_offsets[i]
|
|
col[idx] = B.col + col_offsets[j]
|
|
nnz += B.nnz
|
|
|
|
return coo_matrix((data, (row, col)), shape=shape).asformat(format)
|
|
|
|
|
|
def block_diag(mats, format=None, dtype=None):
|
|
"""
|
|
Build a block diagonal sparse matrix from provided matrices.
|
|
|
|
Parameters
|
|
----------
|
|
mats : sequence of matrices
|
|
Input matrices.
|
|
format : str, optional
|
|
The sparse format of the result (e.g., "csr"). If not given, the matrix
|
|
is returned in "coo" format.
|
|
dtype : dtype specifier, optional
|
|
The data-type of the output matrix. If not given, the dtype is
|
|
determined from that of `blocks`.
|
|
|
|
Returns
|
|
-------
|
|
res : sparse matrix
|
|
|
|
Notes
|
|
-----
|
|
|
|
.. versionadded:: 0.11.0
|
|
|
|
See Also
|
|
--------
|
|
bmat, diags
|
|
|
|
Examples
|
|
--------
|
|
>>> from scipy.sparse import coo_matrix, block_diag
|
|
>>> A = coo_matrix([[1, 2], [3, 4]])
|
|
>>> B = coo_matrix([[5], [6]])
|
|
>>> C = coo_matrix([[7]])
|
|
>>> block_diag((A, B, C)).toarray()
|
|
array([[1, 2, 0, 0],
|
|
[3, 4, 0, 0],
|
|
[0, 0, 5, 0],
|
|
[0, 0, 6, 0],
|
|
[0, 0, 0, 7]])
|
|
|
|
"""
|
|
row = []
|
|
col = []
|
|
data = []
|
|
r_idx = 0
|
|
c_idx = 0
|
|
for a in mats:
|
|
if isinstance(a, (list, numbers.Number)):
|
|
a = coo_matrix(a)
|
|
nrows, ncols = a.shape
|
|
if issparse(a):
|
|
a = a.tocoo()
|
|
row.append(a.row + r_idx)
|
|
col.append(a.col + c_idx)
|
|
data.append(a.data)
|
|
else:
|
|
a_row, a_col = np.divmod(np.arange(nrows*ncols), ncols)
|
|
row.append(a_row + r_idx)
|
|
col.append(a_col + c_idx)
|
|
data.append(a.ravel())
|
|
r_idx += nrows
|
|
c_idx += ncols
|
|
row = np.concatenate(row)
|
|
col = np.concatenate(col)
|
|
data = np.concatenate(data)
|
|
return coo_matrix((data, (row, col)),
|
|
shape=(r_idx, c_idx),
|
|
dtype=dtype).asformat(format)
|
|
|
|
|
|
def random(m, n, density=0.01, format='coo', dtype=None,
|
|
random_state=None, data_rvs=None):
|
|
"""Generate a sparse matrix of the given shape and density with randomly
|
|
distributed values.
|
|
|
|
Parameters
|
|
----------
|
|
m, n : int
|
|
shape of the matrix
|
|
density : real, optional
|
|
density of the generated matrix: density equal to one means a full
|
|
matrix, density of 0 means a matrix with no non-zero items.
|
|
format : str, optional
|
|
sparse matrix format.
|
|
dtype : dtype, optional
|
|
type of the returned matrix values.
|
|
random_state : {numpy.random.RandomState, int}, optional
|
|
Random number generator or random seed. If not given, the singleton
|
|
numpy.random will be used. This random state will be used
|
|
for sampling the sparsity structure, but not necessarily for sampling
|
|
the values of the structurally nonzero entries of the matrix.
|
|
data_rvs : callable, optional
|
|
Samples a requested number of random values.
|
|
This function should take a single argument specifying the length
|
|
of the ndarray that it will return. The structurally nonzero entries
|
|
of the sparse random matrix will be taken from the array sampled
|
|
by this function. By default, uniform [0, 1) random values will be
|
|
sampled using the same random state as is used for sampling
|
|
the sparsity structure.
|
|
|
|
Returns
|
|
-------
|
|
res : sparse matrix
|
|
|
|
Notes
|
|
-----
|
|
Only float types are supported for now.
|
|
|
|
Examples
|
|
--------
|
|
>>> from scipy.sparse import random
|
|
>>> from scipy import stats
|
|
|
|
>>> class CustomRandomState(np.random.RandomState):
|
|
... def randint(self, k):
|
|
... i = np.random.randint(k)
|
|
... return i - i % 2
|
|
>>> np.random.seed(12345)
|
|
>>> rs = CustomRandomState()
|
|
>>> rvs = stats.poisson(25, loc=10).rvs
|
|
>>> S = random(3, 4, density=0.25, random_state=rs, data_rvs=rvs)
|
|
>>> S.A
|
|
array([[ 36., 0., 33., 0.], # random
|
|
[ 0., 0., 0., 0.],
|
|
[ 0., 0., 36., 0.]])
|
|
|
|
>>> from scipy.sparse import random
|
|
>>> from scipy.stats import rv_continuous
|
|
>>> class CustomDistribution(rv_continuous):
|
|
... def _rvs(self, size=None, random_state=None):
|
|
... return random_state.randn(*size)
|
|
>>> X = CustomDistribution(seed=2906)
|
|
>>> Y = X() # get a frozen version of the distribution
|
|
>>> S = random(3, 4, density=0.25, random_state=2906, data_rvs=Y.rvs)
|
|
>>> S.A
|
|
array([[ 0. , 0. , 0. , 0. ],
|
|
[ 0.13569738, 1.9467163 , -0.81205367, 0. ],
|
|
[ 0. , 0. , 0. , 0. ]])
|
|
|
|
"""
|
|
if density < 0 or density > 1:
|
|
raise ValueError("density expected to be 0 <= density <= 1")
|
|
dtype = np.dtype(dtype)
|
|
|
|
mn = m * n
|
|
|
|
tp = np.intc
|
|
if mn > np.iinfo(tp).max:
|
|
tp = np.int64
|
|
|
|
if mn > np.iinfo(tp).max:
|
|
msg = """\
|
|
Trying to generate a random sparse matrix such as the product of dimensions is
|
|
greater than %d - this is not supported on this machine
|
|
"""
|
|
raise ValueError(msg % np.iinfo(tp).max)
|
|
|
|
# Number of non zero values
|
|
k = int(round(density * m * n))
|
|
|
|
random_state = check_random_state(random_state)
|
|
|
|
if data_rvs is None:
|
|
if np.issubdtype(dtype, np.integer):
|
|
def data_rvs(n):
|
|
return rng_integers(random_state,
|
|
np.iinfo(dtype).min,
|
|
np.iinfo(dtype).max,
|
|
n,
|
|
dtype=dtype)
|
|
elif np.issubdtype(dtype, np.complexfloating):
|
|
def data_rvs(n):
|
|
return (random_state.uniform(size=n) +
|
|
random_state.uniform(size=n) * 1j)
|
|
else:
|
|
data_rvs = partial(random_state.uniform, 0., 1.)
|
|
|
|
ind = random_state.choice(mn, size=k, replace=False)
|
|
|
|
j = np.floor(ind * 1. / m).astype(tp, copy=False)
|
|
i = (ind - j * m).astype(tp, copy=False)
|
|
vals = data_rvs(k).astype(dtype, copy=False)
|
|
return coo_matrix((vals, (i, j)), shape=(m, n)).asformat(format,
|
|
copy=False)
|
|
|
|
|
|
def rand(m, n, density=0.01, format="coo", dtype=None, random_state=None):
|
|
"""Generate a sparse matrix of the given shape and density with uniformly
|
|
distributed values.
|
|
|
|
Parameters
|
|
----------
|
|
m, n : int
|
|
shape of the matrix
|
|
density : real, optional
|
|
density of the generated matrix: density equal to one means a full
|
|
matrix, density of 0 means a matrix with no non-zero items.
|
|
format : str, optional
|
|
sparse matrix format.
|
|
dtype : dtype, optional
|
|
type of the returned matrix values.
|
|
random_state : {numpy.random.RandomState, int, np.random.Generator}, optional
|
|
Random number generator or random seed. If not given, the singleton
|
|
numpy.random will be used.
|
|
|
|
Returns
|
|
-------
|
|
res : sparse matrix
|
|
|
|
Notes
|
|
-----
|
|
Only float types are supported for now.
|
|
|
|
See Also
|
|
--------
|
|
scipy.sparse.random : Similar function that allows a user-specified random
|
|
data source.
|
|
|
|
Examples
|
|
--------
|
|
>>> from scipy.sparse import rand
|
|
>>> matrix = rand(3, 4, density=0.25, format="csr", random_state=42)
|
|
>>> matrix
|
|
<3x4 sparse matrix of type '<class 'numpy.float64'>'
|
|
with 3 stored elements in Compressed Sparse Row format>
|
|
>>> matrix.todense()
|
|
matrix([[0.05641158, 0. , 0. , 0.65088847],
|
|
[0. , 0. , 0. , 0.14286682],
|
|
[0. , 0. , 0. , 0. ]])
|
|
|
|
"""
|
|
return random(m, n, density, format, dtype, random_state)
|