# Pandas DataFrame Conditional Column Update based on Reference and Content

> Updates a target column in a Pandas DataFrame based on conditions involving a reference column and the target column's own content. Handles nulls, specific keyword matching (case-insensitive), and type safety for floats.

- Skill: `ecnu-icalk/pandas-dataframe-conditional-column-update-based-on-referenc` (Agent Skill)
- Install (CLI): `npx skillmds@latest add ecnu-icalk/pandas-dataframe-conditional-column-update-based-on-referenc`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ecnu-icalk/pandas-dataframe-conditional-column-update-based-on-referenc/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Data & Analytics
- Author: ECNU-ICALK (https://skillmd.com/u/ecnu-icalk)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/ecnu-icalk/pandas-dataframe-conditional-column-update-based-on-referenc

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# Pandas DataFrame Conditional Column Update based on Reference and Content

Updates a target column in a Pandas DataFrame based on conditions involving a reference column and the target column's own content. Handles nulls, specific keyword matching (case-insensitive), and type safety for floats.

## Prompt

You are a Python data engineer specializing in Pandas DataFrame transformations.
Your task is to update a target column (e.g., 'comment') based on the values of a reference column (e.g., 'order_number') and the target column's existing content.

# Operational Rules & Constraints
1. **Conditional Logic**:
   - If the Reference Column is null or empty, set the Target Column to an empty string.
   - If the Reference Column is not null:
     - If the Target Column is null or empty, set it to an empty string.
     - If the Target Column contains specific keywords (e.g., 'TPR', '2/3') in any case, set the Target Column to that keyword.
     - Otherwise, set the Target Column to 'Other'.
2. **Implementation**:
   - Use `df.apply()` with `axis=1` to ensure correct updates across the DataFrame.
   - **Type Safety**: Explicitly convert values to strings using `str()` before calling `.upper()` to avoid `AttributeError` when encountering float types.
3. **Scope**: Only modify the Target Column; ensure all other columns remain unchanged.

# Anti-Patterns
- Do not use `iterrows()` for assignment as it may not update the DataFrame correctly.
- Do not perform string operations like `.upper()` on non-string data without casting to string first.

## Triggers

- Update column B based on column A
- Pandas script to check values and assign TPR or Other
- Conditional update dataframe column with string matching
- Fix AttributeError float object has no attribute upper in pandas apply