replacing all row values with shorter names in pandas

Question

I have a big data set with tons of rows. I have one column in that data set with long row values. I want to rename these row values with shorter names in pandas automatically. What should I do?

My data is something like this:

and I want an output like this:

Answer 1

What you are looking for is the pd.factorize function which encodes the different patterns of objects as an enumerated type (with different serial numbers). You can use it as follows:

df['Col1'] = 'C' + pd.Series(pd.factorize(df['Col1'])[0] + 1, dtype='string')

or if your Pandas version does not support string dtype, use:

df['Col1'] = 'C' + pd.Series(pd.factorize(df['Col1'])[0] + 1).astype(str) 

Demo

Data Input

data = {'Col1': ['XXXXXXXXXXXXXX', 'YYYYYYYYYYYYYY', 'XXXXXXXXXXXXXX', 'YYYYYYYYYYYYYY', 'XXXXXXXXXXXXXX', 'ZZZZZZZZZZZZZZ']}
df = pd.DataFrame(data)

print(df) 


             Col1
0  XXXXXXXXXXXXXX
1  YYYYYYYYYYYYYY
2  XXXXXXXXXXXXXX
3  YYYYYYYYYYYYYY
4  XXXXXXXXXXXXXX
5  ZZZZZZZZZZZZZZ

Output:

print(df)

  Col1
0   C1
1   C2
2   C1
3   C2
4   C1
5   C3

Answer 2

Use:

df['col1'] = 'C' + (df.groupby('Col1').ngroup() + 1).astype(str)