Fix boolean contour defaults (swev-id: matplotlib__matplotlib-24870)

[casey-brooks]

Summary

• detect boolean Z arrays before type conversion
• default auto contour levels for bool inputs to binary thresholds
• add regression coverage for bool, masked, and lognorm cases

Testing

• PYTEST_ADDOPTS='-W ignore::DeprecationWarning' MPLBACKEND=Agg PYTHONPATH=/workspace/matplotlib/lib LD_LIBRARY_PATH=/nix/store/qipd93x9gjyiygqk673rd2ssnf8y7jj0-gcc-14.3.0-lib/lib:/nix/store/f8w1i7yisixb9hivzbk0l4ixmf67fjqr-gcc-14.3.0-libgcc/lib:/nix/store/4wdz42ns29ys6fm1xak68bnp51nxhd2s-zlib-1.3.1/lib .venv/bin/pytest lib/matplotlib/tests/test_contour.py -k 'bool'
• PYTHONPATH=/workspace/matplotlib/lib .venv/bin/flake8 lib/matplotlib/contour.py lib/matplotlib/tests/test_contour.py

Resolves #43

[casey-brooks]

Test & Lint Summary

• PYTEST_ADDOPTS='-W ignore::DeprecationWarning' MPLBACKEND=Agg PYTHONPATH=/workspace/matplotlib/lib LD_LIBRARY_PATH=/nix/store/qipd93x9gjyiygqk673rd2ssnf8y7jj0-gcc-14.3.0-lib/lib:/nix/store/f8w1i7yisixb9hivzbk0l4ixmf67fjqr-gcc-14.3.0-libgcc/lib:/nix/store/4wdz42ns29ys6fm1xak68bnp51nxhd2s-zlib-1.3.1/lib .venv/bin/pytest lib/matplotlib/tests/test_contour.py -k 'bool' (6 passed, 0 failed)
• PYTHONPATH=/workspace/matplotlib/lib .venv/bin/flake8 lib/matplotlib/contour.py lib/matplotlib/tests/test_contour.py (no issues)

[noa-lucent]

Thanks for wiring up the boolean default levels and adding coverage. Please also update the public docs (Axes.contour/contourf docstrings and What's New) to reflect the new behaviour so the issue is fully resolved.

[casey-brooks]

Hi @noa-lucent — I've added the Axes.contour/contourf docstring note about boolean Z inputs and documented the change in What's New. Re-ran the focused contour tests and flake8; everything is green. Ready for another look when you have a chance.

[noa-lucent]

Docs look good now—thanks for adding the What’s New entry and docstring note. Approving.