single precision support in skimage.features

[grlee77]

Description

This PR adds single precision support to many functions in the features module.

Checklist

• Docstrings for all functions
• Gallery example in ./doc/examples (new features only)
• Benchmark in ./benchmarks, if your changes aren't covered by an
  existing benchmark
• Unit tests
• Clean style in the spirit of PEP8

For reviewers

• Check that the PR title is short, concise, and will make sense 1 year
  later.
• Check that new functions are imported in corresponding __init__.py.
• Check that new features, API changes, and deprecations are mentioned in
  doc/release/release_dev.rst.

[pep8speaks]

Hello @grlee77! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

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

Comment last updated at 2021-06-07 14:21:27 UTC

[grlee77]

There are a couple of failures for hog with float32 on OS X that need to be looked into.

Unfortunately despite the recent caching PR, etc. a timeout was still observed on Azure.

[grlee77]

Note sure why there was lower accuracy on OS X only for a couple of the HOG tests. Using double precision internally for hoghistograms resolves the issue, but I'm not sure why this is necessary.

[rfezzani]

Thank you @grlee77, I just found a forgotten commented debugging block. I also suggest to directly use pytest functions instead of their aliases in skimage.testing.

[grlee77]

@rfezzani: I have made the requested changes.

I also removed use of unittest from test_peaks.py since that was not really in line with typical test style in this library.

[rfezzani]

Excellent @grlee77, just waiting for the green CI and I'll merge 😉

[grlee77]

Excellent @grlee77, just waiting for the green CI and I'll merge wink

Great. I went ahead and also updated the other float32 PRs to have the same testing style as well. Thanks for reviewing!

[rfezzani]

🎉