Before this: Hand off a cleaning job: rules, exceptions, reconciliation
The idea
A handoff note lets a colleague trust, rerun and question your work without asking you.
Include: the rules in the order applied, assumptions, a reconciliation table, exceptions by reason with examples, open questions with owners, and how to rerun.
Keep it short and factual; link to the code and the exception file rather than pasting them.
Worked example
Input: orders.csv → clean_orders + exceptions
- Visual
(document) Rules · Reconciliation · Exceptions · Questions · Rerun
- SQL (DuckDB)
SELECT reason, COUNT(*) FROM exceptions GROUP BY ALL ORDER BY 2 DESC
- pandas
exceptions["reason"].value_counts()
Result: Input 1,000 = clean 951 + exceptions 49 (bad_timestamp 21, unknown_customer 18, duplicate 10)
Common mistakes
- No counts.
- Assumptions left implicit.
- No way to rerun.
Check yourself
What proves nothing was lost?
The reconciliation: input rows equal clean rows plus exceptions.
Practice it
Clean the export and report exceptions by reason.