create id from a sorted visit frequency data

[ffgsdf]

Hi everyone, 

If i have a data which is the following

data t;INPUT x;

cards;
1
2
1
2
3
1
2
; 

This data set is merged from each person. 

So, its id should be 1 1 2 2 2 3 3.

How could I get the the id I want? I have tried use the if first statement, but I failed. 

Please tell me the easiest way to do it. 

[Astounding · Accepted solution]

This would be one way:

data want;

set have;

priorx = lag(x);

if _n_=1 or x <= priorx then id + 1;

drop priorx;

run;

This assumes that when X stays the same from one observation to the next, that the ID should be different.

Good luck.