'src_indices best practices

After ver. 3.13 src_indices is changed, I could not find it in docs. Could you share a sample code for connecting a smaller portion of a large matrix?

i.e. source is 5x5 matrix and target is 2x2 starting from [2,3]



Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source