Export to mpl figure

[zingale]

PR Summary

This reissues #2497

A common operation is to make a matplotlib figure and grid of axes to display slice plots or projection plots, e.g., as shown in this cookbook recipe:

https://yt-project.org/docs/dev/cookbook/complex_plots.html#multipanel-with-axes-labels

This adds a method to PWViewerMPL to automate a lot of that setup. E.g., you would now do that recipe as:

import yt

ds = yt.load_sample("IsolatedGalaxy")

fields = ['density', 'velocity_x', 'velocity_y', 'velocity_magnitude']
p = yt.SlicePlot(ds, 'z', fields)
p.set_log('velocity_x', False)
p.set_log('velocity_y', False)

fig = p.export_to_mpl_figure((2,2))
fig.tight_layout()

fig.savefig("test.png")

PR Checklist

• pass flake8 yt/
• pass isort . --check --diff
• pass black --check yt/
• New features are documented, with docstrings and narrative docs
• Adds a test for any bugs fixed. Adds tests for new features.

[neutrinoceros]

Apart from the stylistic issues caught by travis this still looks good to me ! thanks for reissuing this !

[zingale]

I think I fixed all the style issues now.

[neutrinoceros]

ah, sorry this didn't work ! make sure you have the latest versions for black and isort, older ones may produce different results that won't pass the CI check !

edit: I was looking at the previous jobs apparently, sorry !

[munkm]

This is excellent, and think this is a really nice tool for our users! Thank you so much for the reissue @zingale !!!!

I think it would be nice if you could add an existing example of using this (and maybe also doing some subsequent operations on the matplotlib object) in the narrative docs. The set you linked to seems like a good place. Would you mind adding another section there with this function being used too?

[zingale]

@munkm I could either rewrite the above linked cookbook example to use this, or add an example right afterwards that shows how to do that more easily -- what do you think?

[munkm]

I think adding an example right afterwards to show how to do it more easily would be great -- that way users can see two methods to get the same result!

[zingale]

done! a new cookbook script appears after the original now.

[zingale]

this is the output from the new cookbook example:

[munkm]

You rock! And this feature rocks!!! 🤘 🎸 🚀 Thank you so much @zingale ! I'll merge once the tests pass. 🙂