Do not enable default Matplotlib backend when checking what the backend is #38
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The test image changes are on the |
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I've converted this to Draft as there are changes planned in Matplotlib that will make the fix different and better. |
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This is now ready. After this is merged I would like a new release. |
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Sorry I missed that ping me if this get delayed. |
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I've made you maintainer to unblock you a bit. |
This was referenced Mar 3, 2025
timhoffm
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since 3.10 we have the official API `matplotlib.get_backend (auto_select=False)`. No problems have been reported and matplotlib-inline is using it https://github .com/ipython/matplotlib-inline/pull/38. Therefore, I remove the provisional status from the auto-select flag. Additionally, I deprecate the API rcParams._get('backend'), which the above is replacing. It seems that `rcParams._get("backend")` is not used anywhere publically, but let's still be defensive and deprecate. https://github.com/search?q=%2F%5C._get%5C%28%5B%22%27%5Dbackend%5B%22%27%5D%5C%29%2F+language%3APython+NOT+is%3Afork+NOT+path%3A**%2Fmatplotlib%2F**+NOT+path%3A**%2Fsite-packages**+NOT+path%3A**%2Fpyplot.py&type=code This is working towards matplotlib#26406. Follow-up to matplotlib#29039.
timhoffm
added a commit
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that referenced
this pull request
Jan 14, 2026
since 3.10 we have the official API `matplotlib.get_backend (auto_select=False)`. No problems have been reported and matplotlib-inline is using it https://github .com/ipython/matplotlib-inline/pull/38. Therefore, I remove the provisional status from the auto-select flag. Additionally, I deprecate the API rcParams._get('backend'), which the above is replacing. It seems that `rcParams._get("backend")` is not used anywhere publically, but let's still be defensive and deprecate. https://github.com/search?q=%2F%5C._get%5C%28%5B%22%27%5Dbackend%5B%22%27%5D%5C%29%2F+language%3APython+NOT+is%3Afork+NOT+path%3A**%2Fmatplotlib%2F**+NOT+path%3A**%2Fsite-packages**+NOT+path%3A**%2Fpyplot.py&type=code This is working towards matplotlib#26406. Follow-up to matplotlib#29039.
timhoffm
added a commit
to timhoffm/matplotlib
that referenced
this pull request
Jan 14, 2026
since 3.10 we have the official API `matplotlib.get_backend (auto_select=False)`. No problems have been reported and matplotlib-inline is using it https://github .com/ipython/matplotlib-inline/pull/38. Therefore, I remove the provisional status from the auto-select flag. Additionally, I deprecate the API rcParams._get('backend'), which the above is replacing. It seems that `rcParams._get("backend")` is not used anywhere publically, but let's still be defensive and deprecate. https://github.com/search?q=%2F%5C._get%5C%28%5B%22%27%5Dbackend%5B%22%27%5D%5C%29%2F+language%3APython+NOT+is%3Afork+NOT+path%3A**%2Fmatplotlib%2F**+NOT+path%3A**%2Fsite-packages**+NOT+path%3A**%2Fpyplot.py&type=code This is working towards matplotlib#26406. Follow-up to matplotlib#29039.
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Fixes #37 and #25.
When importing
backend_inlinethe function_enable_matplotlib_integration()is automatically called and this checks what the current Matplotlib backend is. Previously callingmatplotlib.get_backend()if no backend was currently set would as a side-effect force it to be the default backend for that OS rather than leaving it unset. Changing it tomatplotlib.rcParams._get("backend")avoids the side-effect thus fixing the problem.Although
rcParams._getis a private function this is in fact the correct function to use as explained in the Matplotlib source code:https://github.com/matplotlib/matplotlib/blob/eb812a8e479d0bcf43a30232c31afec78963ed53/lib/matplotlib/__init__.py#L698-L713
To reproduce the original problem and confirm this PR fixes it use the following on the
mainbranch and this PR branch:~/.ipython/profile_default/ipython_kernel_config.pycontaining the single linec.InteractiveShellApp.matplotlib = 'inline'.jupyter laborjupyter qtconsoleand run the following code:import matplotlib.pyplot as plt; plt.plot([1,3,2])On
mainbranch this uses the wrong Matplotlib backend and on this PR branch it used the correctinlinebackend.I have manually tested other use cases of using Matplotlib in
ipythonandjupyterand it looks like this fix does not introduce any new problems.