Pandas new column based on value from another column

May 15, 2024

How can I add a new column to dataframe that has the same name as values in another column?

My dataframe is:

import pandas as pd
df = pd.DataFrame({
    'Col1': [2, 74, 37, 36, 95],
    'Col2': [36, 80, 9, 26, 16],
    'Col3': [20, 4, 7, 55, 91],
    'Col4': ['Col2','Col2','Col2','Col2','Col2']
})

So I need to add new column ‘Col0’ with values from column ‘Col2’ because it’s name is the same as values in Col4.

The result I want is:

df = pd.DataFrame({
    'Col1': [2, 74, 37, 36, 95],
    'Col2': [36, 80, 9, 26, 16],
    'Col3': [20, 4, 7, 55, 91],
    'Col4': ['Col2','Col2','Col2','Col2','Col2'],
    'Col0': [36, 80, 9, 26, 16]
})

>Solution :

Try:

df["Col0"] = df.apply(lambda row: row[row["Col4"]], axis=1)
print(df)

Prints:

   Col1  Col2  Col3  Col4  Col0
0     2    36    20  Col2    36
1    74    80     4  Col2    80
2    37     9     7  Col2     9
3    36    26    55  Col2    26
4    95    16    91  Col2    16