Pandas: resample timeseries with groupby

Question

Given the below pandas DataFrame:

In [115]: times = pd.to_datetime(pd.Series([\'2014-08-25 21:00:00\',\'2014-08-25 21:04:00\',
                                       


        

Answer 1

Pandas 0.21 answer: TimeGrouper is getting deprecated

There are two options for doing this. They actually can give different results based on your data. The first option groups by Location and within Location groups by hour. The second option groups by Location and hour at the same time.

Option 1: Use groupby + resample

grouped = df.groupby('Location').resample('H')['Event'].count()

Option 2: Group both the location and DatetimeIndex together with groupby(pd.Grouper)

grouped = df.groupby(['Location', pd.Grouper(freq='H')])['Event'].count()

They both will result in the following:

Location                     
HK        2014-08-25 21:00:00    1
LDN       2014-08-25 21:00:00    1
          2014-08-25 22:00:00    2
Name: Event, dtype: int64

And then reshape:

grouped.unstack('Location', fill_value=0)

Will output

Location             HK  LDN
2014-08-25 21:00:00   1    1
2014-08-25 22:00:00   0    2