Regex Tester

Where regex earns its keep for analysts

It is the fastest way to pull structured values out of messy free text — emails from a notes column, order IDs from a description, dates in the wrong format — and to find the rows that don't match a pattern, which are usually the dirty ones. The same expressions drop into SQL's REGEXP, pandas' str.extract and spreadsheet regex functions.

The flags, quickly

g finds every match, not just the first. i ignores case. m makes^ and $ match line starts/ends. s lets . match newlines too.