Fix top_k for multiclassf1score

[rittik9]

What does this PR do?

Fixes #1653

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📚 Documentation preview 📚: https://torchmetrics--2839.org.readthedocs.build/en/2839/

[eneserdo]

Thanks for the effort. Imho, you could have handled the "refining" on directly preds tensor using something like this:

preds_topk = torch.argsort(preds, dim=-1, descending=True)[:, :top_k]
preds_top1 = preds_topk[:, 0]
preds=torch.where((target.view(-1, 1) == preds_topk).sum(dim=-1).bool(), target, preds_top1)

Which is more compact way of doing the same job. (Cloning and reshaping are omitted here)

Also, these changes will break the current tests for all top_k related classes/functions e.g. for recall, accuracy, f1, so on so forth. I think it is important to re-write these tests. Additionally, maybe for the topk accuracy you can take the scikit learn's top_k_accuracy_score as a reference.

[rittik9]

Thanks for your suggestions.I've noticed some of the tests have failed. I'm working on them. I am also comparing them with other library implementations. I'll keep updating here.

[codecov]

Codecov Report

Attention: Patch coverage is 11.11111% with 8 lines in your changes missing coverage. Please review.

Project coverage is 41%. Comparing base (0d3494f) to head (aa8ff49).

❗ There is a different number of reports uploaded between BASE (0d3494f) and HEAD (aa8ff49). Click for more details.

HEAD has 226 uploads less than BASE

Flag	BASE (0d3494f)	HEAD (aa8ff49)
macOS	15	3
python3.10	45	9
cpu	70	14
torch2.0.1	10	2
torch2.0.1+cpu	15	3
Windows	10	2
python3.12	15	3
torch2.5.0	5	1
torch2.5.0+cpu	5	1
gpu	1	0
unittest	1	0
Linux	45	9
torch2.4.1+cu121	10	2
torch2.1.2+cpu	5	1
python3.11	5	1
torch2.3.1+cpu	5	1
torch2.2.2+cpu	5	1
torch2.5.0+cu124	10	2
python3.9	5	1

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #2839     +/-   ##
========================================
- Coverage      69%     41%    -28%     
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  Files         346     332     -14     
  Lines       19129   18962    -167     
========================================
- Hits        13227    7736   -5491     
- Misses       5902   11226   +5324     

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