PR Summary

I made the negative_linestyles for contours toggle-able via kwarg. The only way to toggle this currently is with rcParams.

I am re-opening this issue from a fresh branch. There was some discussion in #23102.

In the attached issue, we had some discussion on whether this is a good idea or not, but I think it is worth considering. We can maintain current functionality and just apply the kwarg if it is defined. This will not break previous functionality. I wrote some tests for this, but I know they can be improved. I'm not completely certain on using baseline_images with parametrized inputs.

Please use this PR and the attached issue to discuss whether this is a good idea or not. I'm happy to take this in a different direction if there are some better ideas!

Closes #23028

Previous

plt.rcParams['contour.negative_linestyle'] = 'solid'
fig, ax = plt.subplots()
CS = ax.contour(X, Y, Z, 6, colors='k')  # Negative contours default to dashed.
ax.clabel(CS, fontsize=9, inline=True)
ax.set_title('Single color - negative contours solid')

With this PR

fig2, ax2 = plt.subplots()
CS = ax2.contour(X, Y, Z, 6, colors='k', negative_linestyles='solid')
ax2.clabel(CS, fontsize=9, inline=True)
ax2.set_title('Single color - negative contours solid')

PR Checklist

Tests and Styling

• Has pytest style unit tests (and pytest passes).
• Is Flake 8 compliant (install flake8-docstrings and run flake8 --docstring-convention=all).

Documentation

• New features are documented, with examples if plot related.
• New features have an entry in doc/users/next_whats_new/ (follow instructions in README.rst there).
• API changes documented in doc/api/next_api_changes/ (follow instructions in README.rst there).
• Documentation is sphinx and numpydoc compliant (the docs should build without error).