sparse.save_npz(filename, matrix, compressed=True)[source]

Save a sparse matrix to disk in numpy’s .npz format. Note: This is not binary compatible with scipy’s save_npz(). Will save a file that can only be opend with this package’s load_npz().

  • filename (string or file) – Either the file name (string) or an open file (file-like object) where the data will be saved. If file is a string or a Path, the .npz extension will be appended to the file name if it is not already there

  • matrix (COO) – The matrix to save to disk

  • compressed (bool) – Whether to save in compressed or uncompressed mode


Store sparse matrix to disk, and load it again:

>>> import os
>>> import sparse
>>> import numpy as np
>>> dense_mat = np.array([[[0., 0.], [0., 0.70677779]], [[0., 0.], [0., 0.86522495]]])
>>> mat = sparse.COO(dense_mat)
>>> mat
<COO: shape=(2, 2, 2), dtype=float64, nnz=2, fill_value=0.0>
>>> sparse.save_npz('mat.npz', mat)
>>> loaded_mat = sparse.load_npz('mat.npz')
>>> loaded_mat
<COO: shape=(2, 2, 2), dtype=float64, nnz=2, fill_value=0.0>
>>> os.remove('mat.npz')