moveaxis doesn't support negative indices

[asmeurer]

The moveaxis method doesn't support negative indices. Something like

if source < 0: source = axes[source]
if target < 0: target = axes[target]

should fix it. It also doesn't support lists of indices like NumPy.

[lanking520]

Hi @asmeurer thanks for your issue,
asked someone to take a look here: @apeforest @samskalicky

[apeforest]

@mxnet-label-bot Add [Operator]

[ifeherva]

I have an implementation already just need to ask tests and will PR.

[ifeherva]

See PR here
#14321

[haojin2]

Closing the issue since it's been fixed, also in the new mxnet.np module:

>>> from mxnet import np
>>> x = np.zeros((3, 4, 5))
>>> np.moveaxis(x, [0, 1], [-1, -2]).shape
(5, 4, 3)