Time Series & MultiIndex
Working with dates, and indexing by more than one level at once.
A MultiIndex lets a DataFrame be indexed by more than one key at once.
This is common after a groupby on multiple columns, or when representing
naturally hierarchical data like (date, ticker).
💡 Tip: np.busday_offset(dates, offsets=-10, roll='backward') shifts dates by business days, rolling non-business days back to the nearest valid one first.
Now practice it
Exercises that use what this lesson just covered.