Unique value count based on two-columns group
Dataframe is like
col1 col2 col3 Col4 Col5....
-----------------------------------
1: A S1 X110
2: A S1 X110
3: A S2 X212
4: B S3 X311
5: A S2 X212
6: A S1 X150
7: B S3 X311
8: C S4 X222
9: C S4 X222
10: C S4 X222
11: A S1 X150
12: A S2 X200
13: A S2 X211
14: B S3 X311
15: B S3 X311
data = {'Col1':['A', 'A', 'A', 'B', 'A', 'A', 'B', 'C', 'C', 'C', 'A', 'A', 'A', 'B', 'B'],
'Col2':['S1','S1','S2','S3','S2','S1','S3','S4','S4','S4','S1','S2','S2','S3','S3'],
'Col3':['X110','X110','X212','X311','X212','X150','X311','X222','X222','X222','X150',
'X200','X211','X311','X311'] }
df = pd.DataFrame(data)
I want to count unique (distinct) combinations of col1 and col2 for each value of col3.
A & S2 have three unique combinations X212, X200, X211.
so the result for that combination is 3.
Expected output is
col1 col2 Count
--------------------------
1: A S1 2
2: A S2 3
3: B S3 1
5: C S4 1
