Just a short question about removing rows

[hellorc]

Closed

[PeterClemmensen · Accepted solution]

Try this

data have;
input patient_id week condition @@;
datalines;
1 1 0 
1 2 1 
1 3 3 
2 2 2 
2 5 1 
3 1 3 
4 2 0 
4 3 1 
4 4 1 
4 5 2 
;
run;

data want(drop = flag);
   set have;
   by patient_id;
   if first.patient_id then flag = 0;
   if flag = 0 then output;
   if condition = 1 then flag = 1;
   retain flag;
run;

Result:

patient_id week condition
1          1    0
1          2    1
2          2    2
2          5    1
3          1    3
4          2    0
4          3    1

[Quentin]

Nothing is easy. : )

Can you show the code you have tried?  Did it involve RETAIN?  That will help others help you.