python, pandas - how to replace values in a data frame column

Question

I have a following code which suppose to create a new column "TEMP1" which is a column "TEMP" with some replacements - replace #1 to a value of column PARM1:

import pandas as pd
d = {'col1': [1, 2], 'TEMP': ['kk(#1,#2)', 'kk(#1,#2)'], 'PARM1':['VAR1','VAR2'], 'PARM2':['VAR3','VAR1']}
df = pd.DataFrame(data=d)
df['TEMP1']=df['TEMP'].to_string(index=False).replace('#1',df['PARM1'].to_string(index=False))
print(df)

what i get is:

   col1       TEMP PARM1 PARM2                                 TEMP1
0     1  kk(#1,#2)  VAR1  VAR3  kk(VAR1\nVAR2,#2)\nkk(VAR1\nVAR2,#2)
1     2  kk(#1,#2)  VAR2  VAR1  kk(VAR1\nVAR2,#2)\nkk(VAR1\nVAR2,#2)

so, instead of using only value of PARM1 in the same row, it replaces with all values of PARM1 separated by a new line symbol what i need is just

kk(VAR1,#2)
kk(VAR2,#2)

Answer 1

If your table format is pretty stable you could do something like this

d = {'col1': [1, 2], 'TEMP': ['kk(#1,#2)', 'kk(#1,#2)'], 'PARM1':['VAR1','VAR2'], 'PARM2':['VAR3','VAR1']}
df = pd.DataFrame(data=d)
df['TEMP1'] = df['TEMP']
for i in range(0, len(df)):
    df.at[i, 'TEMP1'] = df.iloc[i]['TEMP1'].replace('#1', df.iloc[i]['PARM1'])
df