topic Re: scanning a row to find 2 consecutive values that are equal in SAS Programming

scanning a row to find 2 consecutive values that are equal

GreggB — Fri, 16 Dec 2016 21:20:33 GMT

My data set consists of grade progressions of students over 13 school years (04-05 to 16-17). Every student identified has been retained at least once during his/her enrollment in our system. My task is to identify which school year the retention occured. The header row represents the school year, e.g. grade17 is the 16-17 school year, grade16 is the 1516 school year, etc. The values represent the grade the student was in. A zero stands for kindergarten; a missing value means the student was not enrolled in that particular year.

Student 1 should be flagged as being retained in grade 12 after the 14-15 school year and the 15-16 school year.

Student 2 should be flagged as being retained in grade 10 after 13-14 school year.

Student 3 should be flagged as being retained in grade 0 (kindergarten) after the 05-06 school year.

ID	grade17	grade16	grade15	grade14	grade13	grade12	grade11	grade10	grade09	grade08	grade07	grade06	grade05
1	12	12	12	11	10	9	9	7	6	5	4	3	2
2	12	11	10	10	9	.	.	.	.	.	.	.	.
3	10	9	8	7	6	5	4	3	2	1	0	0	.

Re: scanning a row to find 2 consecutive values that are equal

Reeza — Fri, 16 Dec 2016 21:31:10 GMT

Is number 1 i your example correct?

Re: scanning a row to find 2 consecutive values that are equal

Reeza — Fri, 16 Dec 2016 21:32:40 GMT

Arrays are one of the easiest ways to do this.

Look at the example titled

Identify patterns across variables using arrays

Re: scanning a row to find 2 consecutive values that are equal

ballardw — Fri, 16 Dec 2016 21:44:10 GMT

What actual VALUE do you want in your flag variable? it is not clear from your question what your output data set would look like.

Also what is the actual rule when there are multiple choices such as with ID=1?

This will set a flag for the "latest" grade for a student or none if there are no sequences.

data want;
   set have;
   array g {5:17} grade05-grade17;
   do i = 17 to 6 by -1;
      if not missing(g[i]) and g[i-1] = g[i] then do;
        Flag=g[i];
        leave;
      end;
   end;
run;

Re: scanning a row to find 2 consecutive values that are equal

GreggB — Mon, 19 Dec 2016 14:06:28 GMT

Yes, it's correct. He was retained twice. I may have to ignore multiple retentions. There's only a handful.

Re: scanning a row to find 2 consecutive values that are equal

GreggB — Mon, 19 Dec 2016 14:10:26 GMT

I actually need 2 flags - one to show the grade in which the student was retained and the other to show when he was retained. For student 2, it would grade_retained = 10 and when_retained = grade14

Re: scanning a row to find 2 consecutive values that are equal

GreggB — Wed, 04 Jan 2017 17:50:41 GMT

Thanks for the info. I need to think through my data some more and what I really want to accomplish.

Re: scanning a row to find 2 consecutive values that are equal

GreggB — Wed, 04 Jan 2017 17:51:51 GMT

Thank you for the code. I need to think more about what I want as my end result.