Try to fix issue #2437

[LunnyRia]

Summary

This PR removes cell_coloring_property from VoronoiGrid and sets it as an argument when visualizing.

Bug / Issue

Related to Minor refactoring of VoroinoiGrid #2437.

Implementation

In voronoi.py, there are three instances where the cell_coloring_property attribute is mentioned. All of these instances should be commented out (but not deleted). By examining mpl_space_drawing.py, I found that this attribute is used to set the transparency (alpha) of polygons. Based on the last line of voronoi.py, I understand that the developer intended to set its value to 0. However, I don’t quite understand why it was defined as a str, as indicated by cell_coloring_property: str | None = None.

To enable setting the transparency of Voronoi polygons during visualization, I modified mpl_space_drawing.py. In the draw_voronoi_grid function, I added this attribute as a new parameter. GPT and Claude suggested more refined approaches for this visualization, but I want to first confirm that my modification doesn’t introduce any bugs and hear your opinions on it.

Testing

Using the .pre-commit-config.yaml file from the root folder of the Mesa project, I ran pre-commit run --all-files locally, and all checks passed.

Additional Notes

I just started learning Mesa and look forward to your suggestions. Thank you!

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
BoltzmannWealth	small	🔵 +0.3% [-1.2%, +1.7%]	🔵 -0.3% [-0.4%, -0.1%]
BoltzmannWealth	large	🔵 +1.3% [+0.5%, +2.0%]	🔵 -1.0% [-2.6%, +0.2%]
Schelling	small	🔵 +0.1% [-0.2%, +0.4%]	🔵 -0.5% [-0.6%, -0.4%]
Schelling	large	🔵 -1.0% [-3.9%, +0.6%]	🔵 +2.3% [+1.8%, +2.8%]
WolfSheep	small	🔵 -0.3% [-0.7%, +0.1%]	🔵 +0.6% [-0.4%, +1.7%]
WolfSheep	large	🔵 -0.4% [-0.9%, +0.1%]	🔵 -0.9% [-2.2%, +0.6%]
BoidFlockers	small	🔵 -0.6% [-1.3%, +0.0%]	🔵 -1.0% [-1.9%, +0.0%]
BoidFlockers	large	🔵 -1.0% [-1.7%, -0.3%]	🔵 -0.1% [-0.7%, +0.5%]

[quaquel]

Thanks for taking a stab at this issue.

1. Can you make the title a bit more descriptive?
2. Why don't you delete the old code?
3. This version of the PR removes functionality: i.e., we can no longer control the alpha of the individual voroinoi cells. How difficult would it be to modify draw_voronoi_grid to accept a color and/or alpha kwarg?