Feature/shap utils

[Alex6022]

Dear @Scienfitz and @AdrianSosic,

As you previously offered in PR #335, I have taken a shot at integrating SHAP analysis amongst other explainers provided by the SHAP package. Similar to the Polars integration, it is provided as an optional dependency. As suggested, I have included tests, ensured it works with hybrid spaces and molecular encodings, implemented it as another utility and decoupled the computation and plotting methods. It also uses the exposed surrogate implemented in PR #355.

The Explanation object provided by the SHAP package can be created through
shap_kern = explanation(campaign)

This object can then be passed to the plotting functions wrapped from the SHAP package:
plot_beeswarm(shap_kern)

Additionally, this implementation allows users to selected whether to use the computational or experimental representation of the search space. E.g., while the experimental representation can give a good overview of the important parameters:

, the computational representation can give more advanced users the option to understand which encodings specifically predict the target:

Please let me know if you have any further input for improving this. Looking forward to it!

[AdrianSosic]

Hi @Alex6022, awesome that you gave it a shot 🎖️ I just returned from my vacation on the weekend. Let me have a thorough look at the code, exchange with @Scienfitz, and then we'll share with you our consolidated thoughts 👍🏼

[Scienfitz]

sorry for taking long, busy days :) but we see your contribution 👍
I'm leaving some initial comments here (and theres also something for you in #357), as I took a first look now, I'll discuss the structure question with the others, some more requests especially regarding the main file will definitely come later

[Alex6022]

Dear @Scienfitz,
Thank you for the feedback. I have improved the code according to each input from you in this PR and also generalized the code for other SHAP explainers according to your suggestion in #357. Please let me know when and how I should adjust the main functionality according to the overall strategy for this feature :).

[Scienfitz]

Thank you @Alex6022
fantastic that it could be generalized
In the meantime we came to a conclusion about the structure. I've summarized everything at the top of #357 as tick-off box. Please let me know if you have any questions in the thread. I hope this should mostly only require renamings and moving your already built code around

after that I dont really see any more major changes for now and we should be ready for the full review and finish line 🎉