how to compare two columns in pandas to make a third column ?

Question

i have two columns age and sex in a pandas dataframe

sex = [\'m\', \'f\' , \'m\', \'f\', \'f\', \'f\', \'f\']
age = [16 ,  15 , 14 , 9  , 8   , 2   , 56 ]
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Answer 1

You could use pandas.DataFrame.where. For example

child.where(age<=9, sex)