Question

I’d like to roll a 2D numpy array, except that I’d like to fill the ends with zeros rather than roll the data as if it were periodic.

The following

import numpy as np

x = np.array([[1, 2, 3], [4, 5, 6]])

np.roll(x, 1, axis=1)

returns

array([[3, 1, 2], [6, 4, 5]])

but what I would prefer is

array([[0, 1, 2], [0, 4, 5]])

Answer 1

I don’t think that you are going to find an easier way to do this that is built-in. The touch-up seems quite simple to me:

y = np.roll(x,1,axis=1)
y[:,0] = 0

If you want this to be more direct then maybe you could copy the roll function to a new function and change it to do what you want. The roll() function is in the site-packages\core\numeric.py file.