csr_matrix與ndarray類型互轉

ndarry 轉 csr_matrix
>>> import numpy as np
>>> import scipy.sparse

>>> my_matrix = scipy.sparse.csr_matrix((2,2))
>>> my_array = my_matrix.A
>>> type(my_array)
numpy.ndarray
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csr_matrix 轉 ndarray
>>> import numpy as np
>>> from scipy import sparse
>>> A = np.array([[1,2,0],[0,0,3],[1,0,4]])

>>> A
array([[1, 2, 0],
[0, 0, 3],
[1, 0, 4]])

>>> sA = sparse.csr_matrix(A) # Here's the initialization of the sparse matrix.

>>> sA
<3x3 sparse matrix of type '<type 'numpy.int32'>'
with 5 stored elements in Compressed Sparse Row format>

>>> print sA
(0, 0) 1
(0, 1) 2
(1, 2) 3
(2, 0) 1
(2, 2) 4