Python Pandas : pivot table with aggfunc = count unique distinct

Question

df2 = pd.DataFrame({\'X\' : [\'X1\', \'X1\', \'X1\', \'X1\'], \'Y\' : [\'Y2\',\'Y1\',\'Y1\',\'Y1\'], \'Z\' : [\'Z3\',\'Z1\',\'Z1\',\'Z2\']})

    X   Y   Z
0  X1  Y2         


        

Answer 1

Do you mean something like this?

In [39]: df2.pivot_table(values='X', rows='Y', cols='Z', 
                         aggfunc=lambda x: len(x.unique()))
Out[39]: 
Z   Z1  Z2  Z3
Y             
Y1   1   1 NaN
Y2 NaN NaN   1

Note that using len assumes you don't have NAs in your DataFrame. You can do x.value_counts().count() or len(x.dropna().unique()) otherwise.