Calculations on groups of rows

So far, you have learned how to do operations for every row of a dataset. Now you are ready to go beyond this. Suppose that you have a list of daily temperatures in a given country over a year. You may want to know the overall average temperature, the average temperature by region, or the coldest day in the year. When you work with data, these kinds of calculations are a common requirement. In this section, you will learn how to address these requirements with Kettle.