ENH: functions to add from scikit-learn

[lithomas1]

• fill_diagonal
  • Uses in sklearn https://github.com/search?q=repo%3Ascikit-learn%2Fscikit-learn%20fill_diagonal&type=code
  • I know its not always possible to make this inplace like in numpy. I think it'd be still useful to have an implementation of this (that returns a new array if it can't be inplace) in array-api-extra, since it's so common.
• isin/in1d
  • The main usage here is in the encode module I think https://github.com/scikit-learn/scikit-learn/blob/32aa82d25725d4bc0dfd7707e5c0f8d1387a1ea6/sklearn/utils/_encode.py#L11
  • This might be a nice complement to setdiff1d too.

[lucascolley]

sounds good, PRs welcome!

We already have a private helper from in1d at

array-api-extra/src/array_api_extra/_lib/_utils/_helpers.py

Line 37 in 6e3ad0f

def in1d(

, so isin can be added on top of that