CODE EXAMPLE FOR PYTHON

how to use group by in python to get 15 mins candle data from 1 min candle

df.resample("5T").mean()
Out[8]: 
                       OPEN    HIGH     LOW   CLOSE  VOLUME 
DATE_TIME                                                   
1997-02-03 09:00:00  3046.0  3048.5  3046.0  3047.5    505.0
1997-02-03 09:05:00  3047.6  3047.9  3046.8  3047.3    159.6
1997-02-03 09:10:00  3045.6  3045.9  3044.8  3045.0    110.2
1997-02-03 09:15:00  3043.6  3044.0  3042.8  3043.2     69.2
1997-02-03 09:20:00  3044.7  3045.2  3044.5  3045.0     65.8
1997-02-03 09:25:00  3043.8  3044.0  3043.5  3043.7     59.0
1997-02-03 09:30:00  3044.6  3045.0  3044.3  3044.6     56.0
1997-02-03 09:35:00  3044.5  3044.5  3043.5  3044.5     44.0