Specify that both by and level should not be specified in groupby - GH40378

[GivyBoy]

• closes BUG: TypeError when trying to group on column name and index level at the same time #40378
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

Ref: #47778 (comment)

[mroeschke]

Thanks for the pull request, but I believe this was addressed by #47778?

Also, please fill out the pull request template to give more context to reviewers. Thanks.

[rhshadrach]

The docs change looks good. As mentioned in #40378 (comment), I think we should also be raising an error when both by and level are specified. If you'd like to address that here, I'd be +1. Not doing so is also okay - we can have it addressed in a separate PR.

[rhshadrach]

@mroeschke: #47778 (comment)

@GivyBoy: When doing a PR that is following up from a conversation, it's helpful for reviews today as well as developers way in the future to reference it in the OP. So I would recommend adding here:

Ref: #47778 (comment)

[rhshadrach]

@GivyBoy - I think this looks good; can you merge main and resolve conflicts.

[rhshadrach]

It looks like the merge restored the line

The argument validation should be done in ``.groupby()``, using the name of the specific index.

This is the one that should be removed.

[rhshadrach]

In the user guide we're losing the sentence

When using .groupby() on a DatFrame with a MultiIndex, do not specify both by and level.

But I think that's okay (API docs seems sufficient to me). @mroeschke - thoughts?

[mroeschke]

In the user guide we're losing the sentence

When using .groupby() on a DatFrame with a MultiIndex, do not specify both by and level.

But I think that's okay (API docs seems sufficient to me). @mroeschke - thoughts?

Yeah I think that's fine. Generally I favor things in the API docs over the user guide as I'm guessing the API docs get more visibility.

[mroeschke]

Thanks @GivyBoy