Grouping by a Timestamp and another column

The .resample method is unable to group by anything other than periods of time. The .groupby method, however, has the ability to group by both periods of time and other columns.

In this recipe, we will show two very similar but different approaches to group by Timestamps and another column.

How to do it…

1. Read in the employee dataset, and create a DatetimeIndex with the HIRE_DATE column:

   >>> employee = pd.read_csv('data/employee.csv',
   ...     parse_dates=['JOB_DATE', 'HIRE_DATE'],
   ...     index_col='HIRE_DATE')
   >>> employee
               UNIQUE_ID  ...   JOB_DATE
   HIRE_DATE              ...
   2006-06-12          0  ... 2012-10-13
   2000-07-19          1  ... 2010-09-18
   2015-02-03          2  ... 2015-02-03
   1982-02-08          3  ... 1991-05-25
   1989-06-19          4  ... 1994-10-22
   ...               ...  ...        ...
   2014-06-09       1995  ... 2015-06-09...