PR Summary

Replaces #20016

We often want a grid of fixed-aspect ratio axes, but constrained_layout and tigt_layout leave large blank spaces between the axes because they only work with the original axes positions, not the aspect-modified versions.

Here I proposed an extension to constrianed_layout that works for simple grids of axes...

Old:

New:

Code

import matplotlib.pyplot as plt
import numpy as np

nrows = 2
ncols = 3
for compress in ['constrained', 'compressed']:
    print('compress?', compress)
    fig, axs = plt.subplots( nrows, ncols, figsize=(4,4),
                            layout=compress,
                            sharex=True, sharey=True)
    fig.patch.set_facecolor("0.9")
    #fig.set_constrained_layout_pads(compress=True)

    for i in range(nrows):
        for j in range(ncols):
            ax = axs[i, j]
            ax.set_aspect(1)
            pc = ax.pcolormesh(np.random.randn(30, 30))
    axs[0, 1].set_xlabel('Boooo')
    fig.colorbar(pc, ax=axs)

Failures...

This isn't perfect, and that is why it is not in "constrained_layout" Folks should be able to turn this off... This example isn't terrible, but its not very good either, though

fig, axs = plt.subplot_mosaic([['A', 'B', 'B'], ['C', 'D', 'E']], layout='compressed',
                            sharex=True, sharey=True)
for k in axs:
    axs[k].imshow(X)

Or:

fig, axs = plt.subplot_mosaic([['A', 'B', 'B'], ['C', 'B', 'B']], layout='compressed',
                            sharex=True, sharey=True, figsize=(3, 7))

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).