Python/Pandas: Converting numbers by comma separated for thousands

Question

I have a dataframe with a column containing long numbers. I am trying to convert all the values in the numbers column to comma separated for thousands.

df

col_1      col_2
Rooney     34590927
Ronaldo    5467382
John       25647398

How do I iterate and get the following result?
Expected result:

col_1      col_2
Rooney     34,590,927
Ronaldo    5,467,382
John       25,647,398

Answer 1

apply format function to col_2

df = df.assign(col_2=df.col_2.astype(int).apply('{:,}'.format))

     col_1       col_2
0   Rooney  34,590,927
1  Ronaldo   5,467,382
2     John  25,647,398

Answer 2

d = len(list(df.columns))

i.e d=22

d = d-2 and we want to convert only 20 columns

for x in df.columns[-d:]:
     df[x] = [(locale.format("%d", a, grouping=True)) for a in df[x]]

This will solve the problem and dynamically make it comma separated.