topic Re: Can we use descending function in data step ? in SAS Programming

Can we use descending function in data step ?

ajay_mishra — Tue, 09 Jan 2018 18:11:45 GMT

Kurt_Bremser — Tue, 09 Jan 2018 18:16:45 GMT

PGStats — Tue, 09 Jan 2018 18:41:31 GMT

If you mean to read a dataset in reverse order, backwards from the end, here is one way:

data ssalc;
set sashelp.class(obs=1) nobs=nobs;
do i = nobs to 1 by -1;
    set sashelp.class point=i;
    output;
    end;
drop i;
run;

WarrenKuhfeld — Tue, 09 Jan 2018 20:51:48 GMT

Since NOBS=NOBS is taken care of at compile time, here is an alternative to @PGStats code.

data ssalc(drop=i);
   do i = nobs to 1 by -1;
      set sashelp.class point=i nobs=nobs;
      output;
   end;
   stop;
run;

PGStats — Tue, 09 Jan 2018 20:47:50 GMT

Test it! I did.

It will work because it will hit the obs=1 limit after the first iteration. It's just another way to avoid an infinite loop.

WarrenKuhfeld — Tue, 09 Jan 2018 20:50:08 GMT

Sorry @PGStats, I stand corrected. I will update that post.