Shear a numpy array

Question

I\'d like to \'shear\' a numpy array. I\'m not sure I\'m using the term \'shear\' correctly; by shear, I mean something like:

Shift the first column by 0 places

Answer 1

The approach in tom10's answer can be extended to arbitrary dimensions:

def shear3(a, strength=1, shift_axis=0, increase_axis=1):
    if shift_axis > increase_axis:
        shift_axis -= 1
    res = numpy.empty_like(a)
    index = numpy.index_exp[:] * increase_axis
    roll = numpy.roll
    for i in range(0, a.shape[increase_axis]):
        index_i = index + (i,)
        res[index_i] = roll(a[index_i], -i * strength, shift_axis)
    return res