flag nonidentical values within a group

[wcw2]

I need to do a data check that will flag any numeric values that are not identical to others in a group, see below. The first GROUPNO value of each group will always be correct. Thanks.

OBS   GROUPNO   FLAG (want)
1                6
2                6
3                6
4                5                x
5                6
6                6
7                6
8              20
9              21                x
10            20
11            20
12            20

[FreelanceReinh · Accepted solution]

Hello @wcw2,

You'll need an additional variable (like variable grp in the example below) designating the groups or some other criterion to tell SAS where a new group begins.

data have;
input grp GROUPNO;
cards;
1 6
1 6
1 6
1 5
1 6
1 6
1 6
2 20
2 21
2 20
2 20
2 20
;

data want(drop=_g1);
set have;
by grp;  /* add NOTSORTED option if needed */
if first.grp then _g1=groupno;
else if groupno ne _g1 then FLAG='x';
retain _g1;
run;

[wcw2]

Yes indeed. Thanks so very much!