Calculate difference in days between two dates for all possible pairwise date combinations

[Solsidan]

Hi there,

I need your help in solving a problem using SAS. I am interested in calculating the difference in the number of days between all possible pairwise date combinations (from Date_1 to Date_7) for each id.

The eventual goal is to have a single variable indicator ("lessthan400days") per id that takes the value of 1 if the difference for ANY pairwise combination is less than 400 days, value = 0 if all possible pairwise combinations are greater, value = . if there is less than two dates for all date range (date_1 to date_7) e.g. variable lessthan400days for id = 1 would be lessthan400days = 1 because the date pairs (date_1 and date_5) has 107 days, or pairs (date_3 and date_4) has 308 days. For ids 4 and 5, variable lessthan400days = .

So here are some tips to work with:

• No need to store the actual calculation results between the pair combinations.
• If any pair combination is less than or equal to 400, the calculations can stop for that id.
• If for an id there is only one date variable, or all dates are missing i.e. no pair e.g. ids 4 and 5, then set value to missing (".")

I have looked at posts that calculate date differences but none seems to do what I hope to achieve.

I shall greatly appreciate your help!

data have;
input id (Date_1-Date_7) (: yymmdd10.) ;
format Date_1-Date_7 yymmdd10.;
cards;
1     2005/07/28  2016/12/23  2011/03/29  2012/01/30  2005/11/11  2016/12/23  2014/04/10
2     2006/06/16  2005/07/13  2007/06/27  2007/06/19  2005/07/13  2010/10/29  2015/09/29
3     2011/08/19  2010/04/12  2010/04/12  2012/08/21  2007/01/12  2015/12/18  2011/09/09
4     .  .  .  .  .  .  .
5     .  2016/01/21  .  .  .  .  .
;
run;

[PaigeMiller · Accepted solution]

data have;
input id (Date_1-Date_7) (: yymmdd10.) ;
array d date_1-date_7;
flag=.;
do i=1 to dim(d)-1;
	do j=(i+1) to dim(d);
	    if not missing(d(j)) and not missing(d(i)) and abs(d(j)-d(i)) < 400 then do;
                flag=1; 
                leave;
            end;
	end;
end;
format Date_1-Date_7 yymmdd10.;
drop i j;
cards;
1     2005/07/28  2016/12/23  2011/03/29  2012/01/30  2005/11/11  2016/12/23  2014/04/10
2     2006/06/16  2005/07/13  2007/06/27  2007/06/19  2005/07/13  2010/10/29  2015/09/29
3     2011/08/19  2010/04/12  2010/04/12  2012/08/21  2007/01/12  2015/12/18  2011/09/09
4     .  .  .  .  .  .  .
5     .  2016/01/21  .  .  .  .  .
;
run;

[Solsidan]

Thank you PaigeMiller, its exactly what I was looking for.