Numerical Computing with Python

How it works...

When using the agg method to perform an aggregation on multiple columns, pandas creates an index object with two levels. The aggregating columns become the top level and the aggregating functions become the bottom level. Pandas displays MultiIndex levels differently than single-level columns. Except for the innermost levels, repeated index values do not get displayed on the screen. You can inspect the DataFrame from step 1 to verify this. For instance, the DIST column shows up only once but it refers to both of the first two columns.

The innermost MultiIndex level is the one closest to the data. This would be the bottom-most column level and the right-most index level.

Step 2 defines new columns by first retrieving the underlying ...