Pandas lambda if
df['equal_or_lower_than_4?'] = df['set_of_numbers'].apply(lambda x: 'True' if x <= 4 else 'False')
Arpan
df['equal_or_lower_than_4?'] = df['set_of_numbers'].apply(lambda x: 'True' if x <= 4 else 'False')
df.loc[df['age1'] - df['age2'] > 0, 'diff'] = df['age1'] - df['age2']