numpy.flip — NumPy v1.24 Manual (original) (raw)

numpy.flip(m, axis=None)[source]#

Reverse the order of elements in an array along the given axis.

The shape of the array is preserved, but the elements are reordered.

New in version 1.12.0.

Parameters:

marray_like

Input array.

axisNone or int or tuple of ints, optional

Axis or axes along which to flip over. The default, axis=None, will flip over all of the axes of the input array. If axis is negative it counts from the last to the first axis.

If axis is a tuple of ints, flipping is performed on all of the axes specified in the tuple.

Changed in version 1.15.0: None and tuples of axes are supported

Returns:

outarray_like

A view of m with the entries of axis reversed. Since a view is returned, this operation is done in constant time.

See also

flipud

Flip an array vertically (axis=0).

fliplr

Flip an array horizontally (axis=1).

Notes

flip(m, 0) is equivalent to flipud(m).

flip(m, 1) is equivalent to fliplr(m).

flip(m, n) corresponds to m[...,::-1,...] with ::-1 at position n.

flip(m) corresponds to m[::-1,::-1,...,::-1] with ::-1 at all positions.

flip(m, (0, 1)) corresponds to m[::-1,::-1,...] with ::-1 at position 0 and position 1.

Examples

A = np.arange(8).reshape((2,2,2)) A array([[[0, 1], [2, 3]], [[4, 5], [6, 7]]]) np.flip(A, 0) array([[[4, 5], [6, 7]], [[0, 1], [2, 3]]]) np.flip(A, 1) array([[[2, 3], [0, 1]], [[6, 7], [4, 5]]]) np.flip(A) array([[[7, 6], [5, 4]], [[3, 2], [1, 0]]]) np.flip(A, (0, 2)) array([[[5, 4], [7, 6]], [[1, 0], [3, 2]]]) A = np.random.randn(3,4,5) np.all(np.flip(A,2) == A[:,:,::-1,...]) True