Return diagonal elements of scipy sparse matrix

Question

Given a scipy.sparse.csr.csr_matrix, is there a quick way to return the elements on the diagonal?

The reason I would like to do this is to compute inv(D) A, where D is a diagonal matrix whose diagonal entries agree with A (A is my sparse matrix, guaranteed to have nonzeros on the diagonal).

Answer 1

Use csr_matrix.diagonal():

Returns the main diagonal of the matrix

Example:

>>> import numpy as np
>>> from scipy.sparse import csr_matrix
>>> mymat = csr_matrix((4, 4), dtype=np.int8)
>>> mymat.diagonal()
array([0, 0, 0, 0], dtype=int8)