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Setting alpha on legend handle changes patch color #11702
Description
Bug report
Bug summary
I occasionally want the alpha value of the patch in a histogram's legend to be different than the alpha value used to plot the legend. However, when I call set_alpha on a legend handle, the color of the patch in the legend changes.
Code for reproduction
import matplotlib.pyplot as plt
plt.hist([1, 2, 3], alpha = 0.25, label = 'data', color = 'red')
legend = plt.legend()
for lh in legend.legendHandles:
lh.set_alpha(1.0)Actual outcome
Work-around
I can get the result I desire if I call set_edgecolor() and set_facecolor():
plt.hist([1, 2, 3], alpha = 0.25, label = 'data', color = 'red')
legend = plt.legend()
for lh in legend.legendHandles:
lh.set_facecolor(lh.get_facecolor())
lh.set_edgecolor(lh.get_edgecolor())
lh.set_alpha(1.0)Expected outcome
Matplotlib version
- Matplotlib v2.2.2
- Installed from Anaconda (default channel)
- Backend: module://ipykernel.pylab.backend_inline
- Jupyter version: 5.5.0
Activity
bpteague commentedon Jul 19, 2018
Seems related to the following lines in
matplotlib.patches.set_alpha:because both
self._original_facecolorandself._original_edgecolorare set toNone.jklymak commentedon Jul 19, 2018
Huh, I thought we squashed that bug. Anyway, the fix is to have the
_original_face/edgecolorsset inset_colorfew lines after. Want to make a PR?bpteague commentedon Jul 19, 2018
It looks like
set_color()callsset_edgecolor()andset_facecolor(), which already update_original_edgecolorand_original_facecolorrespectively.Perhaps
set_color()isn't getting called as the legend is being set up? I tried digging through the legend code, but I don't understandmatplotlib's internals terribly well and got rather lost.jklymak commentedon Jul 19, 2018
Ooops. Yes, you are right. Chasing through legend isn't pretty...
jklymak commentedon Jul 19, 2018
See #11703 - looks like it fixes the problem to me... Thanks for the great report.
bpteague commentedon Jul 19, 2018
Brilliant. #11703 fixes this for me too. Thanks for digging into this for me (-:
jklymak commentedon Jul 19, 2018
Ha we only get to close it when the PR gets merged 😉
bpteague commentedon Jul 19, 2018
I just got so excited! An hour from report to fix is pretty remarkable. Thanks again.
jklymak commentedon Jul 19, 2018
Well, I was annoyed, because I fixed that bug 6 months ago (for markers instead of bars)...
boyob commentedon Apr 3, 2019
How to change the color of font in legend?
timhoffm commentedon Apr 3, 2019
@boyob This is the bug tracker. For help, please use gitter, the mailinglist or stackoverflow. https://matplotlib.org/#need-help