SAS - grouping pairs

Question

I have two variables ID1 and ID2. They are both the same kinds of identifiers. When they appear in the same row of data it means they are in the same group. I want to make a

Answer 1

Please try the below code.

data have;
input ID1 ID2;
datalines;
1     4
1     5
2     5
2     6
3     7
4     1
5     1
5     2
6     2
7     3
;
run;

* Finding repeating in ID1;

proc sort data=have;by id1;run;

data want_1;

    set have;
    by id1;

    attrib flagrepeat length=8.;

    if not (first.id1 and last.id1) then flagrepeat=1;
    else flagrepeat=0;
run;

* Finding repeating in ID2;

proc sort data=want_1;by id2;run;

data want_2;
    set want_1;
    by id2;

    if not (first.id2 and last.id2) then flagrepeat=1;

run;

proc sort data=want_2 nodupkey;by id1 ;run;

data want(drop= ID2 flagrepeat rename=(ID1=ID));
    set want_2;
    attrib Group length=8.;

    if(flagrepeat eq 1) then Group=1;
    else Group=2;
run;

Hope this answer helps.