numpy矩阵反转 np.flip()

numpy.flip(m,axis=None)

• 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: 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.

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.

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 position0 and position1.

** 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

参考：numpy.flip