问题转化为每个ID的x<2的min(2-x)OBS.
proc sql;
create table obs as select min(2-x) as min,no,x from aaa where x<2 group by no having min=(2-x);
quit;

数据集aaa中多一个变量，比如用0表示每个个体中x值小于2并离2最近的观测。

proc sql;
create table wanted as
select a.*, minx
from aaa a left join
(select *, abs(x-2) as y, 0 as minx
from aaa
where x<2
group by 1
having y=min(y)) b
on a.no=b.no and a.x=b.x;
quit;

merge回去 by no x，然后min 不为空FLAG=0;ELSE flag=1

我的答案