pandas tables: Data Tools worked examples

Clean, combine and inspect tables while preserving their meaning.

• pandas groupby aggregation vs transform: group rows or preserve them

  Compute group totals and row-level shares from an explicit table, including missing keys and a zero-total group.

  tutorial · 4 min read

• pandas loc vs iloc: labels, positions and safe assignment

  Use a nonconsecutive integer index to expose label versus position selection, slicing endpoints and aligned assignment.

  tutorial · 4 min read

• Why a pandas merge duplicates rows: validate the keys first

  Calculate a join's row count, reproduce many-to-many expansion, and use validate and indicator to enforce the intended table relationship.

  troubleshooting · 4 min read

• Three pandas projects for beginners, with complete code and output

  Build three pandas projects with complete Python code: clean orders, join product tables and calculate a daily trend. Check outputs and common data mistakes.

  project · 9 min read