CSV Cleaning Without Losing Meaning

What you will work through

• Parse quoted commas, quotation marks and multiline fields correctly.
• Preserve 0012 and 9007199254740993 as exact strings.
• Resolve declared date and decimal conventions without guessing unknown values.
• Reconcile accepted, quarantined and duplicate rows.
• Produce and reopen an export suited to its actual consumer.

Contents

1. 01Write a cleaning contract before touching values
2. 02Parse records rather than splitting visible lines
3. 03Protect identifiers before assigning types
4. 04Resolve dates through declared meaning
5. 05Handle amounts, currencies, blanks, and zeros
6. 06Clean text deliberately and deduplicate by a key
7. 07Choose an export for its actual consumer
8. 08Reconcile every row and test the round trip
9. 09Capstone: deliver the fictional workshop extract
10. 10Answer key and diagnostic repairs

Scope and limitations

• Not a financial audit, currency conversion service, or automatic source correction.
• No universal spreadsheet formula-safety guarantee; intended consumers require their own reopen checks.
• Fixtures are fictional and small; production data may require additional field and volume rules.
• The exercises cover small datasets; test larger files and your receiving software before using them in production.