output observation at each change of occurance for 0, 1

[jenim514]

Hi all,

I have a data set with coded values 0 and 1 that are sorted by subject and date.  Each time the occurrence happens, coded 1.  When stops, coded 0.  If occurrence happens again, then 1  etc.  I want to output the observation by subject at each change of occurrence  (1, 0, back to 1 etc). 

Any ideas how I can set this up?

Subject	Response	Date	Wanted
123	1	10-May-18	X
123	1	22-Jun-18
123	0	30-Jul-18	X
123	1	12-Sep-18	X
125	1	15-Oct-18	X
125	1	16-Oct-18
125	1	15-Nov-18
125	0	1-Dec-18	X
125	0	20-Dec-18

[Tom · Accepted solution]

Use the NOTSORTED keyword on your BY statement.

data want ;
  set have;
  by subject response notsorted;
  if first.response;
run;

[jenim514]

@Tom thank you!

[singhsahab]

If data sorted by subject variable :

DATA WANT (drop=x);
SET HAVE;
BY SUBJECT;
X=IFN(RESPONSE EQ LAG(Response),0,1);
IF X;
RUN;

Thanks

🙂

[Tom]

That will not work if two adjacent subjects happen to have the same value of RESPONSE.