juniorPandas
What is groupby in Pandas?
Updated May 17, 2026
Short answer
groupby splits data into groups, applies functions, and combines results.
Deep explanation
It follows split-apply-combine strategy, enabling aggregation like sum, mean, or custom functions per group.
Real-world example
Calculating average salary per department in HR analytics.
Common mistakes
- Forgetting to select column before aggregation.
Follow-up questions
- What is transform in groupby?
- Difference between agg and apply?