How to replace a list with first element of list in pandas dataframe column?

Question

I have a pandas dataframe df, which look like this:

df = pd.DataFrame({'Name':['Harry', 'Sam', 'Raj', 'Jamie', 'Rupert'],
                   'Country':['USA', "['USA', 'UK', 'India']", "['India', 'USA']", 'Russia', 'China']})

Name           Country

Harry          USA
Sam            ['USA', 'UK', 'India']
Raj            ['India', 'USA']
Jamie          Russia
Rupert         China

Some values in Country column are list, and I want to replace those list with the first element in the list, so that it will look like this:

Name           Country

Harry          USA
Sam            USA
Raj            India
Jamie          Russia
Rupert         China

Answer 1

As you have strings, you could use a regex here:

df['Country'] = df['Country'].str.extract('((?<=\[["\'])[^"\']*|^[^"\']+$)')

output (as a new column for clarity):

     Name                 Country Country2
0   Harry                     USA      USA
1     Sam  ['USA', 'UK', 'India']      USA
2     Raj        ['India', 'USA']    India
3   Jamie                  Russia   Russia
4  Rupert                   China    China

regex:

(             # start capturing
(?<=\[["\'])  # if preceded by [" or ['
[^"\']*       # get all text until " or '
|             # OR
^[^"\']+$     # get whole string if it doesn't contain " or '
)             # stop capturing