Calculations on groups of rows
You just learned to do simple operations for every row of a dataset. Now you are ready to go beyond. Suppose you have a list of daily temperatures of a given country over a year. You may want to know the overall average temperature, the average temperature by region, or the coldest day of the year. When you work with data, these types of calculations are a common requirement. In this section you will learn to address those requirements with PDI.