ID,CLASS,DATE,MRK
1,321,02/12/2016,30
2,321,05/12/2016,40
3,321,06/12/2016,0
4,321,07/12/2016,60
5,321,10/12/2016,70
6,876,5/12/2016,100
7,876,7/12/2016,80

ID,CLASS,DATE,MRK
1,321,02/12/2016,30
2,321,03/12/2016,0
3,321,04/12/2016,0
4,321,05/12/2016,40
5,321,06/12/2016,0
6,321,07/12/2016,60
7,321,08/12/2016,0
8,321,09/12/2016,0
9,321,10/12/2016,70
10,876,5/12/2016,100
11,876,6/12/2016,0
12,876,7/12/2016,80

import pandas as pd

df = pd.read_csv('In.txt')
resampled_df = df.resample('D').mean()
print resampled_df