apache/superset

(low priority) Histogram throws warning in logs in 6.0.0rc4

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#36530 opened on Dec 11, 2025

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good first issueviz:charts:histogram

Description

Bug description

When you load a dashboard with a Histogram chart, or edit one directly, this Pandas warning appears in the logs:

superset_app          | /app/superset/utils/pandas_postprocessing/histogram.py:57: SettingWithCopyWarning: 
superset_app          | A value is trying to be set on a copy of a slice from a DataFrame.
superset_app          | Try using .loc[row_indexer,col_indexer] = value instead
superset_app          | 
superset_app          | See the caveats in the documentation: https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copy
superset_app          |   df[column] = to_numeric(df[column], errors="coerce")

Doesn't seem to be affecting anything in how the application operates, just something to clean up.

Screenshots/recordings

No response

Superset version

master / latest-dev

Python version

I don't know

Node version

I don't know

Browser

Not applicable

Additional context

No response

Checklist

  • I have searched Superset docs and Slack and didn't find a solution to my problem.
  • I have searched the GitHub issue tracker and didn't find a similar bug report.
  • I have checked Superset's logs for errors and if I found a relevant Python stacktrace, I included it here as text in the "additional context" section.

Contributor guide

Tech stack
pythonpandas
Domain
backenddata
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
pandas basicsSuperset development setup
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80
Research direction
The issue is in /app/superset/utils/pandas postprocessing/histogram.py at line 57. The SettingWithCopyWarning occurs when assigning a numeric column. To fix, replace `df[column] = to numeric(...)` with `df.loc[:, column] = to numeric(...)` to avoid the warning. No linked PRs or maintainer clarification needed.