Create Classes within dataset

[seankortschot]

Hello everyone,

I'm not sure how best to phrase my question, so I'll just show the input and desired output:

The input has the first observation of each class marked with a 1 in the "Set" column. The sorting of the data is obviously very important here, as I've essentially binned the observations according to a particular behaviour that we were observing, which is marked by the 1. I want for all observations until the next instance of a 1 to be in the same class.

Set
1
0
0
1
0
0
0
1
1
0
0

The desired output is as follows:

Set	Class
1	1
0	1
0	1
1	2
0	2
0	2
0	2
1	3
1	4
0	4
0	4

Any help is much appreciated.

Cheers,

Sean

[ballardw · Accepted solution]

Something like this should get you started:

data want;
   set have;
   retain class 0;
   class=class+set;
run;

RETAIN is the basic instruction to keep the value of a variable across interations in the data set.

[seankortschot]

Worked perfectly! Thanks!

[mkeintz]

Then mark the useful response as a solution to your topic question.