Delete observations under certain condition

[Zerg]

Hello all,

I currently have a data file looks like:

ID	Year	Var A
1	2000	0
1	2001	0
1	2002	1
1	2003	0
2	2000	0
2	2001	1
2	2002	1
2	2003	1
2	2004	0
3	2001	0
3	2002	0
3	2003	1
3	2004	0
3	2005	1
3	2006	0

What I need is excluding observations with Var A = 0 prior to the first time when Var A = 1 by the group ID. So the outcome of the data needs to look like:

ID	Year	Var A
1	2002	1
1	2003	0
2	2001	1
2	2002	1
2	2003	1
2	2004	0
3	2003	1
3	2004	0
3	2005	1
3	2006	0

How can I code it? Thank you.

[novinosrin · Accepted solution]

data have;
input ID	Year	Var_A;
datalines;
1	2000	0
1	2001	0
1	2002	1
1	2003	0
2	2000	0
2	2001	1
2	2002	1
2	2003	1
2	2004	0
3	2001	0
3	2002	0
3	2003	1
3	2004	0
3	2005	1
3	2006	0
;

data want;
__k=0;
do until(last.id);
set have;
by id;
if Var_A=1 then __k=1;
if __k then output;
end;
drop _:;
run;

[Zerg]

Thank you . It works perfectly. 🙂