Updating percent better than baseline computation

[freddyaboulton]

Pull Request Description

Fixes #1449

• For objectives bounded strictly in the range [0, 1], the percent difference is the absolute difference (not normalized by the baseline)
• For other objectives, division by 0 is now inf rather than nan

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After creating the pull request: in order to pass the release_notes_updated check you will need to update the "Future Release" section of docs/source/release_notes.rst to include this pull request by adding :pr:123.

[codecov]

Codecov Report

Merging #1809 (7ed3582) into main (5c35743) will increase coverage by 0.1%.
The diff coverage is 100.0%.

@@            Coverage Diff            @@
##             main    #1809     +/-   ##
=========================================
+ Coverage   100.0%   100.0%   +0.1%     
=========================================
  Files         252      252             
  Lines       20052    20117     +65     
=========================================
+ Hits        20044    20109     +65     
  Misses          8        8             

Impacted Files	Coverage Δ
evalml/objectives/cost_benefit_matrix.py	100.0% <100.0%> (ø)
evalml/objectives/fraud_cost.py	100.0% <100.0%> (ø)
evalml/objectives/lead_scoring.py	100.0% <100.0%> (ø)
evalml/objectives/objective_base.py	100.0% <100.0%> (ø)
evalml/objectives/standard_metrics.py	100.0% <100.0%> (ø)
evalml/tests/automl_tests/test_automl.py	100.0% <100.0%> (ø)
...lml/tests/objective_tests/test_standard_metrics.py	100.0% <100.0%> (ø)

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[bchen1116]

LGTM!

[bchen1116]

nit-pick but I thought this was an accidental comment rather than on purpose. Maybe we can move it to be next to is_bounded_like_percentage rather than being above?

[chukarsten]

Wouldn't this go next to perfect_score?

[bchen1116]

same comment

[angela97lin]

Thank you for including these range comments. Super helpful 😁

[angela97lin]

Nice work, LGTM! 🥳

Just out of curiosity, what did we decide for 'edge cases' such as the correlation matrix? I guess it's not really what we currently consider as an objective... but was wondering if we decided on anything :3

[chukarsten]

Looks good to me.

[chukarsten]

Wouldn't this go next to perfect_score?

[freddyaboulton]

@angela97lin Correlation is just like MCC in the sense that it's bounded [-1, 1]. I think it's best to not treat like a percentage in that case. If baseline gets a negative score and our pipeline gets a positive score, then I'd want the percent better to be above 100% which isn't always the case if we treat it like a percentage.