Numerical Computing with Python

Grouping for Aggregation, Filtration, and Transformation

One of the most fundamental tasks during a data analysis involves splitting data into independent groups before performing a calculation on each group. This methodology has been around for quite some time but has more recently been referred to as split-apply-combine. This chapter covers the powerful groupby method, which allows you to group your data in any way imaginable and apply any type of function independently to each group before returning a single dataset.

Hadley Wickham coined the term split-apply-combine to describe the common data analysis pattern of breaking up data into independent manageable chunks, independently applying functions to these chunks, and then combining the ...