`numpy:rollaxis`

Signature

def rollaxis(a, axis, start = 0)

Roll the specified axis backwards, until it lies in a given position.

This function continues to be supported for backward compatibility, but you should prefer moveaxis. The moveaxis function was added in NumPy 1.11.

a : ndarray: Input array.
axis : int: The axis to be rolled. The positions of the other axes do not change relative to one another.
start : int, optional: When start <= axis, the axis is rolled back until it lies in this position. When start > axis, the axis is rolled until it lies before this position. The default, 0, results in a "complete" roll. The following table describes how negative values of start are interpreted:

res : ndarray: For NumPy >= 1.10.0 a view of a is always returned. For earlier NumPy versions a view of a is returned only if the order of the axes is changed, otherwise the input array is returned.

import numpy as np
a = np.ones((3,4,5,6))
np.rollaxis(a, 3, 1).shape
np.rollaxis(a, 2).shape
np.rollaxis(a, 1, 4).shape

✓

(3, 5, 6, 4)