How to group by multiple columns and create a new column based on conditions in Python?

aeapen :

I have a data-frame like below and I want to create a new column based a column

Condition

If two or multiple rows contain the same value for Column A and Column B and Column C is unique then row should be assigned unique group name

Input

A           B        C   
Payment    Mark      2  
Payment    Mark      3   
Delayed    Charles   2  
Delayed    Charles   4   
Held       Mark      3   
Held       Charles   4   
Payment    Mark      2   
Payment    Mark      3   
Delayed    Charles   4   
Held       Charles   4

Expected Output

  A        B         C   Cluster
Payment    Mark      2   C1
Payment    Mark      3   C2
Delayed    Charles   2   C3
Delayed    Charles   4   C4
Held       Mark      3   C5
Held       Charles   4   C6
Payment    Mark      2   C1
Payment    Mark      3   C2
Delayed    Charles   4   C4
Held       Charles   4   C6

How can this be done in python

anky_91 :

This is a factorize problem .

One way would be join the columns into a single series and factorize , add 1 and add C in the beginning:

df['Cluster'] = (pd.Series(df[['A','B','C']].astype(str).agg(''.join,1)
               .factorize()[0]).add(1).astype(str).radd('C'))
print(df)

Another way would be similar but with groupby.ngroup

df['Cluster'] = (df.groupby(['A','B','C'],sort=False).ngroup()
                .add(1).astype(str).radd('C'))

         A        B  C Cluster
0  Payment     Mark  2      C1
1  Payment     Mark  3      C2
2  Delayed  Charles  2      C3
3  Delayed  Charles  4      C4
4     Held     Mark  3      C5
5     Held  Charles  4      C6
6  Payment     Mark  2      C1
7  Payment     Mark  3      C2
8  Delayed  Charles  4      C4
9     Held  Charles  4      C6

How to group by multiple columns and create a new column based on conditions in Python?

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