add stacking selector functionality and docstrings

[solegalli]

closes #361
closes #309

Hi @gverbock

I rebased main to solve the pytest errors and add docstring functionality and then cherry picked some of the changes in #361.

I still need to cherry-pick the test changes, and we need to add the confirm_variables functionality to the remaining selectors (except the target mean because we need to fix that in a different PR)

[solegalli]

I think I brought all the changes in PR #361 to this one now.

[solegalli]

Hi @gverbock

It would be great if you can pick up this changes in a new branch and then make a PR to the branch here, stack_sels.

Also, since all classes have the functionality for confirm_variables, instead of adding 1-2 tests per class, can we add 1 generic test in the script check_estimator.py at the root of the package and then call that test from check_estimator_selectors ?

[gverbock]

Hi @solegalli
I see that you have indeed done quite some work. It looks very good. I fetched the stack_sels branch and made a new branch out of it.
Just to be sure we are aligned before I start working on it:

• I see that the confirm_variable is implemented for all selectors it was meant to be implemented.
• I will pick-up the generic test on confirm_variable.
• I am not sure if there is something left after that, what is your view on this?

[solegalli]

• not sure if there is somethi

Hi @gverbock

I am not sure why I did not receive a notification for your last message. I am really sorry I reply only today :_(

I believe I have now added all the necessary changes. Needs a final review to merge.

[solegalli]

Still needs revision:

• remove tests for confirm variables in individual test files (we now have a generic test in estimator_checks.py.
• see if we can add a test in check_confirm_variables in estimator_checks.py initialising the transformers with variables=None.

I think that will be all.