numpy.flip

numpy.flip(m, axis=None)[源代码]

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

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

1.12.0 新版功能.

Parameters:
m : array_like

Input array.

axis : None 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.

在 1.15.0 版更改: None and tuples of axes are supported

Returns:
out : array_like

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

参见

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]]])
>>> flip(A, 0)
array([[[4, 5],
        [6, 7]],
       [[0, 1],
        [2, 3]]])
>>> 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(flip(A,2) == A[:,:,::-1,...])
True