MAINT: stats.moment: rename parameter moment to order

[mdhaber]

Reference issue

What does this implement/fix?

stats.moment has a parameter named moment. Given that the description is

Order of central moment that is returned

and the name of the equivalent argument of scipy.stats.rv_generic.moment is order,

I think the name order would be more appropriate.

This PR renames the parameter in a way that maintains backward compatibility (i.e. use of keyword-argument 'moment' is still allowed as an alias).

Additional information

• This would need approval from the mailing list.
• We could consider deprecating use of kwarg moment instead of leaving it as an alias, but I am not necessarily pushing for it.
• I could refactor the code to actually use order instead of moment, but I chose instead to let moment = order at the top to minimize the diff.

[j-bowhay]

Seems reasonable although I would prefer to deprecate rather than have two ways of doing the same thing. Is there a specific reason for not? Will wait for the mailing list post before reviewing in detail

[mdhaber]

Is there a specific reason for not?

Well, mostly because the keyword moment is not broken. The motivation for renaming rv_generic from n to order was that there was a name collision between the method parameter n and the shape parameter n of some distributions, so something needed to change. Here, we'd only be improving code clarity and consistency, which might not be enough to justify the backward compatibility break.

I'm not sure I can call for a deprecation right now, but I wouldn't oppose it.

[rgommers]

+1 for merging as is (is moment= alias tested? couldn't tell from the diff), and not deprecating. This is more or less a cosmetic change, so deprecating doesn't seem quite right.

[mdhaber]

@rgommers Oops, I got carried away and changed the name everwhere. I added an explicit test.

[steppi]

+1 for merging as is without deprecating.

[j-bowhay]

Can you update the example to use order instead of moment

[mdhaber]

Thanks @j-bowhay. Did a search and replace this time; I think I got the last of the ones that are supposed to be changed.

[mdhaber]

Mailing list post is here:

https://mail.python.org/archives/list/scipy-dev@python.org/thread/ZKKTYNXWAYZKA4YSFFEU2F6GTHE7NARU/

[j-bowhay]

Sorry missed this last time around. Does this comment also need updating? It looks like there might have originally been a moments->moment typo?

[mdhaber]

Fixed, thanks.

[j-bowhay]

Thanks @mdhaber, will leave a few days before merging in case there is anything from the mailing list

[j-bowhay]

Thanks for the reminder @mdhaber, that was a long few days!