rollaxis(a, axis, start=0)¶
Roll the specified axis backwards, until it lies in a given position.
a : ndarray
axis : int
The axis to roll backwards. The positions of the other axes do not change relative to one another.
start : int, optional
The axis is rolled until it lies before this position. The default, 0, results in a “complete” roll.
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.
>>> a = np.ones((3,4,5,6)) >>> np.rollaxis(a, 3, 1).shape (3, 6, 4, 5) >>> np.rollaxis(a, 2).shape (5, 3, 4, 6) >>> np.rollaxis(a, 1, 4).shape (3, 5, 6, 4)