← NumPy & Pandas learning pathNumPy & Pandas · Module 6 of 10
Transforming data
Create columns, apply functions and sort.
📖 Key ideas
- New column: df["total"] = df["price"] * df["qty"].
- apply runs a function per row or value.
- map replaces values using a dict.
- sort_values("marks", ascending=False).
- rename(columns={"old": "new"}).
💡 Real-life example: Transforming data is reshaping clay: same material, more useful shape.
apply()Runs a function across data
map()Maps values using dict or function
sort_values()Sorts by columns
rename()Renames columns