juniorPandas
How to add a new column in Pandas?
Updated May 17, 2026
Short answer
Assign a new column using df['col'] = values.
Deep explanation
Pandas aligns values by index when creating new columns. You can assign constants, computed values, or derived expressions.
Real-world example
Adding tax or discount columns in financial datasets.
Common mistakes
- Mismatched index causing NaN values.
Follow-up questions
- Can you insert column at specific position?
- Does it modify original DataFrame?