How to apply a function to two columns of Pandas dataframe

Question

Suppose I have a df which has columns of \'ID\', \'col_1\', \'col_2\'. And I define a function :

f = lambda x, y : my_function_expres

Answer 1

A simple solution is:

df['col_3'] = df[['col_1','col_2']].apply(lambda x: f(*x), axis=1)