pandas select two columns groupby code example

Example 1: Pandas groupby max multiple columns in pandas

annotations.groupby(['bookid','conceptid'], sort=False)['weight'].max()

Example 2: group by 2 columns pandas

In [11]: df.groupby(['col5', 'col2']).size()
Out[11]:
col5  col2
1     A       1
      D       3
2     B       2
3     A       3
      C       1
4     B       1
5     B       2
6     B       1
dtype: int64