Bug: express bar chart with facet_col and color. It show wrong chart when clicking legend
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- Dominant language
- Python
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Description
Example:
import pandas as pd
import plotly.express as px
data = {
'Category': ['A', 'B', 'A', 'A', 'B', 'A'],
'Date': ['2025-10-11', '2025-10-11', '2025-10-12', '2025-10-13', '2025-10-13', '2025-10-13'],
'Value': [10, 15, 12, 8, 20, 5],
'Group': ['X', 'X', 'Y', 'Y', 'X', 'Y']
}
df = pd.DataFrame(data)
fig = px.bar(df, x='Date', y='Value',color='Category', facet_col="Group")
fig.show()
When click legend Category B to keep Category A only. It's gone for Group=X
Workaround
for trace in fig.data:
trace.width=8200000
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by running the provided pandas and plotly.express px.bar example with facet_col="Group" and color="Category". Reproduce the legend interaction that removes Category A from Group=X, then trace the bar-chart and legend handling involved. Done means clicking a legend item preserves the expected bars in every facet without requiring the width workaround.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- data-visualization
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 48/100