SciPy Recipes

How to do it…

Converting a matrix into its sparse form

Sparse matrices are built using the functions available in scipy.sparse.

In the following example, we will be using the function named csr_matrix to convert a given matrix into its sparse form.

1. Import the relevant packages:

import numpy as npfrom scipy import sparse 

2. Initialize a matrix:

A = np.array([[1,2,0],[0,0,3],[1,0,4]]) 

3. Convert the initialized matrix into a sparse matrix:

sA = sparse.csr_matrix(A) 

4. Check the output of the preceding sparse matrix initialization:

sA<3x3 sparse matrix of type '<class 'numpy.int32'>'        with 5 stored elements in Compressed Sparse Row format> 

Note that the preceding output mentions that there are five stored elements, which is the same as having ...