How to remove string value from column in pandas dataframe

I am trying to write some code that splits a string in a dataframe column at comma (so it becomes a list) and removes a certain string from that list if it is present. after removing the unwanted string I want to join the list elements again at comma. My dataframe looks like this:

df:

   Column1  Column2
0      a       a,b,c
1      y       b,n,m
2      d       n,n,m
3      d       b,b,x

So basically my goal is to remove all b values from column2 so that I get:

df:

   Column1  Column2
0      a       a,c
1      y       n,m
2      d       n,n,m
3      d       x

The code I have written is the following:

df=df['Column2'].apply(lambda x: x.split(','))

def exclude_b(df):
    for index, liste in df['column2].iteritems():
        if 'b' in liste:
            liste.remove('b')
            return liste
        else:
            return liste

The first row splits all the values in the column into a comma separated list. with the function now I tried to iterate through all the lists and remove the b if present, if it is not present return the list as it is. If I print ‘liste’ at the end it only returns the first row of Column2, but not the others. What am I doing wrong? And would there be a way to implement my if condition into a lambda function?

Answer

simply you can apply the regex b,? , which means replace any value of b and , found after the b if exists

df['Column2'] = df.Column2.str.replace('b,?' , '')

Out[238]:
Column1 Column2
0   a   a,c
1   y   n,m
2   d   n,n,m
3   d   x