print(df['date'].values.astype('<M8[h]'))
['2016-12-06T102016-12-06T102016-12-06T092016-12-06T092016-12-06T092016-12-06T112016-12-06T102016-11-06T092016-11-06T092016-11-06T09'
    ]
Pandas groupby hour of the day to dictionary