>>> import numpy as np
>>> from scipy.sparse import csr_matrix, save_npz, load_npz
>>> r = np.array([0, 0, 1, 2, 2, 3, 3, 3])
>>> c = np.array([0, 1, 2, 1, 2, 0, 2, 3])
>>> v = np.array([1, 2, 3, 4, 5, 6, 7, 8])
>>> x=csr_matrix((v, (r,c)), shape=(4,4))
>>> x
<4x4 sparse matrix of type '<class 'numpy.int64'>'
with 8 stored elements in Compressed Sparse Row format>
>>> x.toarray()
array([[1, 2, 0, 0],
[0, 0, 3, 0],
[0, 4, 5, 0],
[6, 0, 7, 8]])
>>> save_npz('file1.npz', x)
>>> x1=load_npz('file1.npz')
>>> x1.toarray()
array([[1, 2, 0, 0],
[0, 0, 3, 0],
[0, 4, 5, 0],
[6, 0, 7, 8]])