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pythonpandaspython-datetime

Pandas Series: get all dates missing from a datetime slice or range

Given a Pandas series and a datetime slice or range of dates, how can I get all dates from the datetime slice or range that are in the series ?

Ex:
       #my date time slice/ date_range
       st = datetime.datetime(2014, 8, 31, 0, 0)
       en = datetime.datetime(2014, 9, 7, 0, 0)
       date_slice = slice(st,en) 
       rng = pd.date_range('08-31-2014', periods=8, freq='D')  

       #my series
       s = pd.Series({'09-01-2014': 1,
                      '09-02-2014': 1,
                      '09-03-2014': np.nan,
                      '09-04-2014': 1,
                      '09-06-2014': 1})

In this example I would like to return an array of dates in str or datetime format

['08-31-2014', '09-05-2014' , '09-07-2014']
Solution

  • DatetimeIndex.difference returns a sorted set difference:

    In [573]: (rng.difference(pd.to_datetime(s.index))).format()
Out[573]: ['2014-08-31', '2014-09-05', '2014-09-07']

In [598]: (rng.difference(pd.to_datetime(s.index))).format(formatter=lambda x: x.strftime('%m-%d-%Y'))
Out[598]: ['08-31-2014', '09-05-2014', '09-07-2014']