How do I create a sequential unique ID starting with 9999 for each new patient ID

[stodo53]

Hi all,

I am working with repeated measures data, and I am trying to create a new unique ID that begins with 9999 for each new patient. If the patient is repeated, I still want them to have the same ID identifier. 

HAVE			WANT
OBS	ID		OBS	ID
1	4CTH101		1	9999001
2	4CTH101		2	9999001
3	4CTH102		3	9999002
4	4CTH102		4	9999002
5	4CTH104		5	9999004
6	4CTH105		6	9999005

I tried this but it creates a unique ID for each new observation. I think I need to integrate my ID variable but not sure how. 

DATA new; SET old;
	id2 = cats(9999,put(_n_,z3.));
RUN;

Thanks!

[PaigeMiller · Accepted solution]

Why isn't there a 9999003 in your WANT data set?

If you data is sorted by ID, this should work:

data want;
     set have;
     by id;
     if first.id then counter+1;
     id2 = cats('9999',put(counter,z3.));
run;

Note: more than 9999 distinct values of ID will cause this to fail.

[stodo53]

That was a typo on my end - I was just trying to show an example of how it would look like. 

This worked! Thanks so much.