Determining the byte size of a scipy.sparse matrix?

A sparse matrix is constructed from regular numpy arrays, so you can get the byte count for any of these just as you would a regular array.

If you just want the number of bytes of the array elements:

>>> from scipy.sparse import csr_matrix
>>> a = csr_matrix(np.arange(12).reshape((4,3)))
>>> a.data.nbytes
88

If you want the byte counts of all arrays required to build the sparse matrix, then I think you want:

>>> print a.data.nbytes + a.indptr.nbytes + a.indices.nbytes
152