def sp_reshape(A, shape, format='csr'):
"""
Reshapes a sparse matrix.
Parameters
----------
A : sparse_matrix
Input matrix in any format
shape : list/tuple
Desired shape of new matrix
format : string {'csr','coo','csc','lil'}
Optional string indicating desired output format
Returns
-------
B : csr_matrix
Reshaped sparse matrix
References
----------
http://stackoverflow.com/questions/16511879/reshape-sparse-matrix-efficiently-python-scipy-0-12
"""
if not hasattr(shape, '__len__') or len(shape) != 2:
raise ValueError('Shape must be a list of two integers')
if format == 'csr':
return zcsr_reshape(A, shape[0], shape[1])
C = A.tocoo()
nrows, ncols = C.shape
size = nrows * ncols
new_size = shape[0] * shape[1]
if new_size != size:
raise ValueError('Total size of new array must be unchanged.')
flat_indices = ncols * C.row + C.col
new_row, new_col = divmod(flat_indices, shape[1])
B = sp.coo_matrix((C.data, (new_row, new_col)), shape=shape)
if format == 'coo':
return B
elif format == 'csc':
return B.tocsc()
elif format == 'lil':
return B.tolil()
else:
raise ValueError('Return format not valid.')
def sp_reshape(A, shape, format='csr'):
"""
Reshapes a sparse matrix.
Parameters
----------
A : sparse_matrix
Input matrix in any format
shape : list/tuple
Desired shape of new matrix
format : string {'csr','coo','csc','lil'}
Optional string indicating desired output format
Returns
-------
B : csr_matrix
Reshaped sparse matrix
References
----------
http://stackoverflow.com/questions/16511879/reshape-sparse-matrix-efficiently-python-scipy-0-12
"""
if not hasattr(shape, '__len__') or len(shape) != 2:
raise ValueError('Shape must be a list of two integers')
if format == 'csr':
return zcsr_reshape(A, shape[0], shape[1])
C = A.tocoo()
nrows, ncols = C.shape
size = nrows * ncols
new_size = shape[0] * shape[1]
if new_size != size:
raise ValueError('Total size of new array must be unchanged.')
flat_indices = ncols * C.row + C.col
new_row, new_col = divmod(flat_indices, shape[1])
B = sp.coo_matrix((C.data, (new_row, new_col)), shape=shape)
if format == 'coo':
return B
elif format == 'csc':
return B.tocsc()
elif format == 'lil':
return B.tolil()
else:
raise ValueError('Return format not valid.')