CODEWITHSUNDEEP
pythonpandasdataframepandas-groupby
Labeeb Nazim
Labeeb Nazim

Reputation: 99

Pandas dataframe - add suffix to column value only if it is repeated

I have a column in a data frame which looks like -

Key
A
B
C
A
A

I want to transform this so that each key has a suffix "_" + "order of occurrence if value is repeated" i.e. to look like -

Key
A_1
B
C
A_2
A_3

Reading related threads I understand it would have to be a play on groupby and cumcount but cant seem to get the final solution. Any help would be appreciated.

Upvotes: 1

Views: 1663

Answers (1)

BENY
BENY

Reputation: 323366

Let us try with cumcount then mask with total count for each group

g = df.groupby('Key')
df['Key'] += g.cumcount().add(1).astype(str).radd('_').mask(g['Key'].transform('count')==1,'')
df
   Key
0  A_1
1    B
2    C
3  A_2
4  A_3

Upvotes: 4

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