Create new SAS observations until number of observations equals other variable? - sas

Question

I am trying to calculate attack rate in some populations using GEE, but at this time only have total number of non-cases. My dataset has individual level data for each case, and a population-wide count for number of non-cases.
In order to do the GEE, I am trying to get create non-case observations so I have one observation for each non-case.
For example:
In this starting data...
PopID CaseNum N_cases N_noncases
14 . 2 3
14 1 . .
14 2 . .
15 . 5 2
15 1 . .
15 2 . .
15 3 . .
15 4 . .
15 5 . .
I would need to create 3 new observations with PopID14 and 2 new observations in PopID 15.
so it would look like this
PopID CaseNum No_case N_cases N_noncases
14 . . 2 3
14 1 . . .
14 2 . . .
14 . 1 . 3
14 . 2 . 3
14 . 3 . 3
15 . . 5 2
15 1 . . .
15 2 . . .
15 3 . . .
15 4 . . .
15 5 . . .
15 . 1 . 2
15 . 2 . 2
Once I have the non-case observations, I'm planning to separate into case-level and population-level datasets before doing my GEE in the case-level dataset.
I have tried a DO-UNTIL loop set to end when no_case=n_noncases, but it just continues forever and never stops.
data test1;
set test;
do until (no_case=n_noncases) ;
no_case +1;
by Popid;
output;
end; run;
I am open to any and all other ways of doing this :) (I also attempted a proc sql, but that went downhill quickly because I have only ever used them to go from case level to population level data, and not vice versa)

Answer 1

Weird but doable.
data have;
input PopID CaseNum N_cases N_noncases;
cards;
14 . 2 3
14 1 . .
14 2 . .
15 . 5 2
15 1 . .
15 2 . .
15 3 . .
15 4 . .
15 5 . .
;
;
;;
run;
data want;
set have;
by popID;
retain nrecs;
if first.popID then
nrecs=N_noncases;
output;
if last.popid then
do;
N_noncases=nrecs;
call missing(caseNum);
do No_case=1 to nrecs;
output;
end;
end;
keep popID Casenum No_case n_cases N_noncases;
run;

Answer 2

Probably clearer if you do it in steps.
Generate the "non-cases" .
data controls;
set have(keep=popid n_noncases);
where n_noncases > 0 ;
do controlnum=1 to n_noncases;
output;
end;
run;
Then combine with the "cases" ;
data want;
set have(where=(not missing(casenum)) controls;
by popid;
run;
If performance is an issue then make the first one a data step view instead.
data controls / view=controls;
...