Useful Coding Tricks

Python

Numpy

Choose a submatrix

We have a square matrix, take: Y = np.arange(16).reshape(4,4). Numpy has a nice option to take specific row column combination. numpy.ix_. The example is as follows:

import numpy as np

Y = np.arange(16).reshape(4,4)

Y[np.ix_([0,3],[0,3])]  # this will chose the columns and rows we need.

TBA