create a flag for each month policy is active

[msf2021]

Hi everyone!

I have a dataset with policies date began between 2018-01-01 and 2019-12-31 (2 years) that has the following info:

policy          policy_beg_date	   policy_end_date
a	           01-02-2018	    06-02-2018
b	           04-02-2019	    02-04-2020
c	           23-12-2019	    03-02-2020
d	           02-02-2019	

policy begining date (date that policy started) and policy end date (date that policy ended - is missing if policy is still active)

I would like to create flags of 13 months (flag_0month, flag_1month,....flag_13month) where i give 1 if policy is active in month 0, month1, and so on....where month0 is the month of beginnig, month1 is month of begining + 1 and so on so i would have something like this:

policy          policy_beg_date	   policy_end_date	month_begining	 month_end	act_month0	act_month1	act_month2
a	            01-01-2018	      06-01-2018	   201801	   201801	   1		
b	            04-02-2019	      02-04-2020	   201902	   202003	   1	             1	            1
c	            23-12-2019	      03-02-2020	   201912	   202002	   1	             1	            1
d	            02-02-2019		                   201902		           1	             1         	    1

Can anyone please help me achivieng this?

I already tryied someting like in this post : https://communities.sas.com/t5/SAS-Programming/How-to-create-a-flag-for-each-month-lying-between-2-d... but i get errors and i think it's not the same as i need.

Thank you!!

[Kurt_Bremser]

So you want to check for only 13 months, even if the policy runs for a longer term?

How many months should be checked if the end date is missing and 13 months from the start date would be in the future?