DEPR: DataFrame.swapaxes

[jorisvandenbossche]

This is listed in the general deprecation issue #18262.

Now that we have a max dimension of 2, i.e. DataFrame (while before you could have a 3D Panel or NDFrame), I don't think there is any use case for swapaxes where it's not exactly the same as transpose().
It's still implemented independently from transpose(), but I think that df.swapaxes(0, 1) and df.swapaxes(1, 0) are the only two valid options and that gives exactly the same as a transpose() (you can do eg df.swapaxes(0, 0) which is a no-op, but this generalization doesn't really seem worth keeping it as a separate method, I would say)

So let's deprecate it? (in favor of transpose())

[phofl]

Yeah I don't see a real use case for this either. +1

[luke396]

take

[rhshadrach]

+1

[rhshadrach]

A potential reason for this is so that np.swapaxes(df) works. See #57351. But I'm not sure that needs to be supported - why can't users just do df.T?