pandas groupby count the number of zeros in a column

Question

I have a dataframe, e.g:

Date             B           C   
20.07.2018      10           8
20.07.2018       1           0
21.07.2018       0           1
21.07.201         


        

Answer 1

Try also:

df.groupby('Date').agg(lambda x: len(x) - x.astype(bool).sum(axis=0))

Output:

Out[48]: 
            B  C
Date            
20.07.2018  0  1
21.07.2018  1  1