[DOC] Replace use of "estimator" term in base object interfaces with more general references

[tpvasconcelos]

Reference Issues/PRs

Depends on #281

What does this implement/fix? Explain your changes.

See #281 (comment) and relevant replies.

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[codecov]

Codecov Report

Attention: Patch coverage is 62.50000% with 9 lines in your changes missing coverage. Please review.

Project coverage is 84.29%. Comparing base (306958d) to head (da1e4ab).
Report is 67 commits behind head on main.

Files with missing lines	Patch %	Lines
skbase/base/_base.py	62.50%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #293      +/-   ##
==========================================
- Coverage   85.07%   84.29%   -0.78%     
==========================================
  Files          45       45              
  Lines        3015     3184     +169     
==========================================
+ Hits         2565     2684     +119     
- Misses        450      500      +50     

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[tpvasconcelos]

@fkiraly I think this is ready to merge/review 👍

[fkiraly]

Mostly agreed, I have one issue that imo we need to resolve.

In some occurrences, I anticipate that using "object" to refer to a class - namely one inheriting from BaseObject - will cause a lot of confusion.

This is because there are python objects - instances of classes - so we are overloading a term that has a much more general meaning.

The most risky instances of these are the case of "object class" or "base object class", because the thing in question is neither a class, nor a base class..

These occcurences - in set_tag, get_tag, get_tags, set_params, get_params I would leave as is, unless we find a better solution. Perhaps we can work with "from self" etc, but that might confuse users who aren't too familiar wit the self concept.

Some solution suggestions:

• get_tags, get_tag - just say "get tags from object and dynamic tag overrides" etc. Or change it completely, to "get tag value, with key-wise inheritance", then explain inheritance in another sentence.
• get_class_tags, get_class_tag - "from class, with key-wise inheritance"?
• set_params - I've removed the "base" (commit above), I think that fixes the ambiguity since we're not mentioning "class"

Other comments:

• create_test_instance, does not create an instance of BaseObject, but of cls
• "sub-estimator" sounds strange. Component objects?

[fkiraly]

@tpvasconcelos, are you still working on this?

[fkiraly]

Made changes to clarify docs; reverted changes to _clone to avoid a divergence from sklearn.