python - Pandas - Dataframe.set_index - how to keep the old index column

Question

I have this Dataframe:

import pandas as pd
df = pd.DataFrame({\'Hugo\' : {\'age\' : 21, \'weight\' : 75},
                   \'Bertram\': {\'age\' :         


        

Answer 1

The below is the most efficient since it appends the new index of age and makes sure its inplace

df.set_index('age',append=True,inplace=True)