I'd like to add 1 if date_ > buy_date larger than 12 months else 0
example df
customer_id date_ buy_date
34555 2019-01-01 2017-02-01
24252 2019-01-01 2018-02-10
96477 2019-01-01 2017-02-18
output df
customer_id date_ buy_date buy_date>_than_12_months
34555 2019-01-01 2017-02-01 1
24252 2019-01-01 2018-02-10 0
96477 2019-01-01 2018-02-18 1