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FIX: use requested style for empty bar charts. - #31973

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vossvayne wants to merge 1 commit into
matplotlib:mainfrom
vossvayne:issue-21506
Open

FIX: use requested style for empty bar charts.#31973
vossvayne wants to merge 1 commit into
matplotlib:mainfrom
vossvayne:issue-21506

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@vossvayne

@vossvayne vossvayne commented Jun 30, 2026

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PR summary

Issue: Bar has no child patches when input data is empty, this leads to the legend handle being left at default as there are no children.

Fix: Store the style information as a fallback and use it when there are no children. This closes #21506.

Example:

import matplotlib.pyplot as plt

ax = plt.figure().add_subplot()
ax.bar([], [], color="red", alpha=0.3, label="empty")
handler = ax.legend().legend_handles[0]
print(handler.get_facecolor()) # (1.0, 0.0, 0.0, 0.3)
print(handler.get_alpha()) # 0.3

AI Disclosure

Fixed manually.

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github-actions Bot commented Jun 30, 2026

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@rcomer rcomer mentioned this pull request Jun 30, 2026
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QuLogic
QuLogic reviewed Aug 11, 2026
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Comment thread lib/matplotlib/tests/test_legend.py
ax.bar([], [], color='red', alpha=0.3, label='empty')
assert mpl.colors.same_color(
ax.legend().legend_handles[0].get_facecolor(),
mpl.colors.to_rgba('red', 0.3),

@QuLogic QuLogic Aug 11, 2026

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You can pass this directly instead of eager resolving it.

Suggested change
mpl.colors.to_rgba('red', 0.3),
('red', 0.3),

Comment thread lib/matplotlib/tests/test_legend.py
Comment on lines +666 to +667
def test_empty_bar_chart_legend_style():
# issue #21506

@QuLogic QuLogic Aug 11, 2026

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Suggested change
def test_empty_bar_chart_legend_style():
# issue #21506
def test_empty_bar_chart_legend_style():

Comment thread lib/matplotlib/tests/test_legend.py
facecolor='red', edgecolor='black', linewidth=3,
label='styled', hatch='//')
handle = ax.legend().legend_handles[0]
assert mpl.colors.same_color(handle.get_edgecolor(), 'black')

@QuLogic QuLogic Aug 11, 2026

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Should you not be checking facecolor as well?

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[Bug]: plt.bar legend displays incorrect style for empty data

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