`scipy.sparse._matrix_io:save_npz`

Signature

def save_npz(file, matrix, compressed = True)

Save a sparse matrix or array to a file using .npz format.

file : str or file-like object: Either the file name (string) or an open file (file-like object) where the data will be saved. If file is a string, the .npz extension will be appended to the file name if it is not already there.
matrix : spmatrix or sparray: The sparse matrix or array to save. Supported formats: csc, csr, bsr, dia or coo.
compressed : bool, optional: Allow compressing the file. Default: True

Store sparse matrix to disk, and load it again:

import numpy as np
import scipy as sp
sparse_array = sp.sparse.csc_array([[0, 0, 3], [4, 0, 0]])

✓

sparse_array
sparse_array.toarray()

✗

array([[0, 0, 3],
       [4, 0, 0]])

sp.sparse.save_npz('/tmp/sparse_array.npz', sparse_array)
sparse_array = sp.sparse.load_npz('/tmp/sparse_array.npz')

✓

sparse_array
sparse_array.toarray()

✗

array([[0, 0, 3],
       [4, 0, 0]])