Numerical Computing with Python

How it works...

There does not exist a predefined pandas function to calculate the maximum number of standard deviations away from the mean. We were forced to construct a customized function in step 2. Notice that this custom function max_deviation accepts a single parameter, s. Looking ahead at step 3, you will notice that the function name is placed inside the agg method without directly being called. Nowhere is the parameter s explicitly passed to max_deviation. Instead, pandas implicitly passes the UGDS column as a Series to max_deviation.

The max_deviation function is called once for each group. As s is a Series, all normal Series methods are available. It subtracts the mean of that particular grouping from each of the values in the ...