[Bug]: title position incorrect for polar plot · Issue #29381 · matplotlib/matplotlib · GitHub

Bug summary

When using a polar coordinate system the plot title overlaps with the axis labels. This worked in 3.9.4 and broke with 3.10.0. This commit broke it: 8abe308 via #28300

Code for reproduction

import matplotlib.pyplot as plt

plt.polar([0, 1], [0, 1])
plt.title('My Title')
plt.savefig('output.png')

Actual outcome

The title overlaps the axis labels

Expected outcome

The title should be above the axis labels

Additional information

This bug happens with the new 3.10 version, but with the 3.9.4 version
I performed a git bisect using this:

 git bisect start

git bisect good v3.9.4

git bisect bad HEAD

a small test script check.py - there's probably a better way, but that's what I came up with. (Note that the issues also comes up when not using `bbox_inches='tight', but this way it was easier to bisect, since I could instrument the image size)

import matplotlib.pyplot as plt
from PIL import Image

def main():
    plt.polar([0, 1], [0, 1])
    plt.title('My Title')
    plt.savefig('output.png', bbox_inches='tight')
    with Image.open('output.png') as img:
        size = img.size

    if size != (453, 464):
        return 1
    else:
        return 0

if __name__ == '__main__':
    raise SystemExit(main())

finally,

git bisect run python3 check.py

After a few steps it yielded this suspicious commit: 8abe308 (cc @rcomer) which was merged in #28300

Operating system

Ubuntu 22.04

Matplotlib Version

3.10.0.dev1180+gc2d502d219

Matplotlib Backend

agg

Python version

3.13.1

Jupyter version

No response

Installation

git checkout

Without having tested in code, I suspect that prior to #28300, l.3006

if (ax.xaxis.get_ticks_position() in ['top', 'unknown']

the “unknown” has likely caught the polar tick.

That has been cut out by a visible check on all tick.label2, an assumption that is correct only for rectangular axes, where label2 corresponds to the top labels of the x axis.

Well I'm glad I left good notes because otherwise what I did would be a mystery to me 😅. From #26150 (comment) Past Me thought another good option would be to return an extra option from get_ticks_position. For the target case, neither top nor bottom ticks were visible due to axis sharing, so it seems sensible to me that get_ticks_position could return "neither" or "none" rather than "unknown" for that case.

Thanks @jkittner for the clear report and for doing the bisect.

that get_ticks_position could return "neither" or "none" rather than "unknown" for that case.

Or “other”?

Why "other"? That seems no more specific than "unknown". For the sharex case we know that neither top nor bottom ticks are visible, so we can explicitly check for that case which is not currently considered by get_ticks_position.

Sorry, maybe out of context because I’m writing from a phone and may have overlooked something.
My thought was that polar ticks are nether “top” nor “bottom” not “unknown”, but in another arrangement.

Ah OK, we could do both "neither" for the sharex case and "other" for the polar case - though I'm not sure how best to detect the polar situation. In any case I propose to leave that question for v3.11 and just partially revert #28300 to fix the bug for v3.10.1 (see #29382).

Fix matplotlib#29381: Add get_title_top() method for custom title pos…

Fix matplotlib#29381: Update title positioning implementation

[Bug]: title position incorrect for polar plot · Issue #29381 · matplotlib/matplotlib · GitHub

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[Bug]: title position incorrect for polar plot #29381

Bug summary

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Expected outcome

Additional information

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[Bug]: title position incorrect for polar plot · Issue #29381 · matplotlib/matplotlib · GitHub

Repository navigation

[Bug]: title position incorrect for polar plot #29381

Description

Bug summary

Code for reproduction

Actual outcome

Expected outcome

Additional information

Operating system

Matplotlib Version

Matplotlib Backend

Python version

Jupyter version

Installation

Activity

timhoffm commented on Dec 27, 2024

rcomer commented on Dec 27, 2024

timhoffm commented on Dec 27, 2024

rcomer commented on Dec 27, 2024

timhoffm commented on Dec 27, 2024

rcomer commented on Dec 27, 2024

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