Bar Chart labels flipped when horizontal=True

[ajhyndman]

Checklist

• I have searched the existing issues for similar issues.
• I added a very descriptive title to this issue.
• I have provided sufficient information below to help reproduce this issue.

Summary

It looks like there is an oversight in the bar_chart function. When selecting horizontal mode, the X and Y labels do not flip places to align with the flipped dataset.

Reproducible Code Example

st.bar_chart(
  data=result, 
  x="GENRE", 
  x_label="movie genre",
  y="AVG",
  y_label="avarage rating",
  horizontal=True,
)

Steps To Reproduce

Render any bar_chart using both the axis label parameters and in horizontal mode.

Expected Behavior

After selecting, horizontal=True, which flips the x and y axes of the chart, I expect the x_label to be printed along the vertical axis and y_label to be printed on the horizontal axis.

Current Behavior

Instead, x_label remains printed on the horizontal axis and y_label along the vertical axis. This means that x_label and x are no longer represented on the same axis.

Is this a regression?

• Yes, this used to work in a previous version.

Debug info

• Streamlit version: snowflake-current
• Python version: snowflake-current
• Operating System: MacOS 26.4.1
• Browser: Firefox

Additional Information

https://snowflakecomputing.atlassian.net/browse/SNOW-3373985

[github-actions]

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[github-actions]

This is a confirmed bug in st.bar_chart when using horizontal=True together with x_label and/or y_label. The root cause is in lib/streamlit/elements/lib/built_in_chart_utils.py in the _get_axis_encodings function (around line 896). When horizontal=True, the code correctly swaps the x/y data columns (so bars render horizontally), but it does not swap the user-provided axis labels. As a result, x_label remains on the horizontal axis and y_label on the vertical axis, even though the data they describe has been flipped to the opposite axis. The fix is straightforward: when building the encodings for horizontal bar charts, also swap x_axis_label and y_axis_label.

Related Issues

• No closely related open issues or duplicates were found. This appears to be a unique bug report.

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