Renaming columns in pandas based on strings in list

Question

Im trying to replace the column names of a dataframe (sens_second_X) based on the strings in a list (updated_fist_stage) being substrings to the column names. updated_fist_stage = ['ccc_230', 'LN_S_P500', 'mf_100'] and

sens_second_X.columns = ['resid', 'ccc_230_TY',
       EQ_ETF', 
       'LN_S_P500_changes', 'mf_100_equity', 'inflows_2009',
        'inflows_2010']

I try to do this as follows:

def renaming_fun(x):
    for var in updated_fist_stage: 
        if var in x:
            return var
        return x
sens_second_X.columns = map(renaming_fun, sens_second_X.columns)

but I get that only ccc_230 has been renamed in the dataframe and the output is as follows:

sens_second_X.columns = ['resid', 'ccc_230',
       EQ_ETF', 
       'LN_S_P500_changes', 'mf_100_equity', 'inflows_2009',
        'inflows_2010']

anky · Accepted Answer · 2020-01-28 16:25:49Z

1

You can try something like below with str.extract

mapped = sens_second_X.columns.str.extract(r'({})'.format('|'.join(updated_fist_stage))
                                                        ,expand=False)
sens_second_X.columns = pd.Index(pd.Series(mapped).fillna(pd.Series(sens_second_X.columns)))

Index(['resid', 'ccc_230', 'EQ_ETF', 'LN_S_P500', 'mf_100', 'inflows_2009',
   'inflows_2010'],
  dtype='object')

answered Jan 28, 2020 at 16:25

anky

75.3k11 gold badges46 silver badges76 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Phoenixo · Accepted Answer · 2020-01-28 16:31:31Z

1

Your return x was just at the wrong indent :

def renaming_fun(x):
    for var in updated_fist_stage: 
        if var in x:
            return var
    return x  # <---- HERE IS THE CHANGE
sens_second_X.columns = map(renaming_fun, sens_second_X.columns)

What happened to you before : the if condition was verified for ccc_230, it returned var, and then it returned x for the rest of the iterator. So the function renaming_fun() was only called once

answered Jan 28, 2020 at 16:31

Phoenixo

2,1631 gold badge9 silver badges14 bronze badges

Collectives™ on Stack Overflow

Renaming columns in pandas based on strings in list

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related