Python Pandas : Pivot table : aggfunc concatenate instead of np.size or np.sum

You can use

agg

groupby

df.groupby(['name', 'age'])['phonenumber'].    agg({'phonecount': pd.Series.nunique,          'phonenumber': lambda x: ','.join(x)        }       )#    phonenumber  phonecount# name  age     #    A   10   Phone1,Phone22#    B   21 PhoneB1,PhoneB22#    C   23          PhoneC1

Or a shorter version according to @root and @Jon Clements:

df.groupby(['name', 'age'])['phonenumber'].   agg({'phonecount': 'nunique', 'phonenumber': ','.join})