TST: account for flakiness with Numpy v1 (part 2) by rcomer · Pull Request #31442 · matplotlib/matplotlib · GitHub
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TST: account for flakiness with Numpy v1 (part 2) - #31442

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jklymak merged 1 commit into
matplotlib:mainfrom
rcomer:minver-flake
Apr 3, 2026
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TST: account for flakiness with Numpy v1 (part 2)#31442
jklymak merged 1 commit into
matplotlib:mainfrom
rcomer:minver-flake

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@rcomer

@rcomer rcomer commented Apr 3, 2026 •
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PR summary

Following #30950, fix the flaky colorbar test in minver in the same way we fixed the flaky pcolor test before. In my local dev environment with Numpy v2.3, I verified that setting vmin slightly higher (vmin=0.100001) reproduces the failure.

I also ran minver multiple times in parallel on my fork and found

  • With no code changes, the colorbar test fails in six runs out of 60. logs
  • If I move the Numpy pin to v2.0.0 (and the contourpy pin to v1.2.1 as that's the first version to support numpy v2), I see no failures in 60 runs. logs
  • If I revert the pins and include the change in this PR, I see no failures in 60 runs. logs

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timhoffm
timhoffm approved these changes Apr 3, 2026
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@timhoffm timhoffm left a comment

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Thanks for the rigorous investigation!

@jklymak

jklymak commented Apr 3, 2026

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@timhoffm

timhoffm commented Apr 3, 2026 •
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I agree that the tick logic could be more robust. However,

  • this is a reasonable quick fix to prevent CI flakiness
  • given that numpy >=2 works I assume numpy has done some improvements on precision handling, so that our ticker doesn’t need added robustness

Overall, ticket robustness could be evaluated as a follow-up, but I don’t see it as a high priority.

@rcomer

rcomer commented Apr 3, 2026

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If vmin is 0.1, wouldn't the 10**-2 tick be off the end of the colorbar anyway?

@jklymak

jklymak commented Apr 3, 2026

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... sorry, whatever the failing tick is

jklymak
jklymak reviewed Apr 3, 2026
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Comment thread lib/matplotlib/tests/test_colorbar.py

@jklymak jklymak Apr 3, 2026

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I assume this is the assertion that fails, and the first tick is 10^{-1} instead of 10^{-2}. The first visible tick is 10^{-1}, so the test is a bit goofy. This basically boils down to our undetermined zeroth tick issue.

I guess this fix is fine here, as we are not testing the ticking, but rather the formatting.,

@rcomer rcomer Apr 3, 2026

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Yes exactly. Sorry, I should have pasted or directly linked the error.

@jklymak
jklymak merged commit f6f7d7a into matplotlib:main Apr 3, 2026
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@rcomer
rcomer deleted the minver-flake branch April 3, 2026 21:36
@rcomer rcomer added this to the v3.11.0 milestone Apr 3, 2026
@QuLogic QuLogic mentioned this pull request Apr 17, 2026
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@jklymak jklymak jklymak approved these changes
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