Find column whose name contains a specific value that is in a fixed column

Question

I have a dataframe with column names, and I want to find the one that contains a certain value. I'm searching for the value in the column 'segment' in column names like '...._segment'. I want the column name to be returned as a string or a variable, so I access the column later with df['name'] or df[name] as normal. enter image description here

Answer 1

I don't know whether you want to get the column names which contain the string you want or the columns name of the columns which have at least one value that contains the string you want.

if the dataframe is:

In [1]: import pandas as pd 
   ...: df = pd.DataFrame({'a_1': ['b_1', 'b_2'], 'b_1': ['a_1', 'a_2']})                                                                             
In [2]: df                                                                                                                                            
Out[2]: 
   a_1  b_1
0  b_1  a_1
1  b_2  a_2

for the first case, if you want to find all the column name that match a_* :

In [3]: import re                                                                                                                                     
In [4]: columns = [col for col in df.columns if isinstance(col, str) and re.match('a_.*', col)]                                                       
In [5]: columns                                                                                                                                       
Out[5]: ['a_1']

for the second case, if you want to find all the columns in which there is at least one value that match a_.* :

In [6]: columns = [col for col, ser in df.iteritems() if ser.str.match('a_.*').any()]                                                                 
In [7]: columns                                                                                                                                       
Out[7]: ['b_1']

in which:

df.iteritems : return a iterator of (column name, column values (series)) pairs.

Series.any : return True if any value in the series is True .