Update metrics to use Enum (#5657)

[yuntai]

Add enum in metrics/classification/helpers.py

• DataType
• AverageMethod
• MDMCAverageMethod

What does this PR do?

Fixes # (5657) <- Update metrics to use Enum #5657

Before submitting

• Was this discussed/approved via a GitHub issue? (not for typos and docs)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• Did you make sure to update the documentation with your changes? (if necessary)
• Did you write any new necessary tests? (not for typos and docs)
• Did you verify new and existing tests pass locally with your changes?
• Did you update the CHANGELOG? (not for typos, docs, test updates, or internal minor changes/refactorings)

PR review

Anyone in the community is free to review the PR once the tests have passed.
Before you start reviewing make sure you have read Review guidelines. In short, see the following bullet-list:

• Is this pull request ready for review? (if not, please submit in draft mode)
• Check that all items from Before submitting are resolved
• Make sure the title is self-explanatory and the description concisely explains the PR
• Add labels and milestones (and optionally projects) to the PR so it can be classified
• Check that target branch and milestone match!

Did you have fun?

Make sure you had fun coding 🙃

[pep8speaks]

Hello @yuntai! Thanks for updating this PR.

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2021-02-01 17:22:28 UTC

[justusschock]

I like it.

[SkafteNicki]

Great job so far @yuntai.
Could you make a similar to Enum type for the average argument here:
https://github.com/PyTorchLightning/pytorch-lightning/blob/817a41d6351839bb2950a5cd7612beb5b39c514e/pytorch_lightning/metrics/classification/helpers.py#L464-L468

[codecov]

Codecov Report

Merging #5689 (7c77ab3) into release/1.2-dev (5d239cc) will decrease coverage by 5%.
The diff coverage is 100%.

@@               Coverage Diff                @@
##           release/1.2-dev   #5689    +/-   ##
================================================
- Coverage               89%     84%    -5%     
================================================
  Files                  169     169            
  Lines                12415   12430    +15     
================================================
- Hits                 11099   10479   -620     
- Misses                1316    1951   +635     

[yuntai]

@SkafteNicki added class AverageMethod and class MDMCAverageMethod in helpers.py and remove AverageMethods from functional/auroc.py

do we want NormalizationMethod for confusion matrix as well?

[justusschock]

@yuntai if this is only used in the confusion matrix, this is probably overkill.

[SkafteNicki]

@yuntai as @justusschock mentions it is probably overkill. I would say that we should only convert code that atleast influences two metrics.

[SkafteNicki]

LGTM :]