topic Re: sum over paired observations in SAS Procedures

sum over paired observations

natson001 — Tue, 07 Oct 2014 18:45:23 GMT

Supposed my dataset like this:

obs x

1 5

2 6

3 9

4 8

5 6

6 7

I want to replace the first obs with the sum of the first and the second (5 replayed by 5+6=11) and the third with the sum of the third and fourth (9 replace by 9+8=17) , etc.

The resulting dataset like this:

obs x

1 11

2 6

3 17

4 8

5 13

6 7

What is the best way to do that?

Thanks!

Andrew

Re: sum over paired observations

Reeza — Tue, 07 Oct 2014 18:52:57 GMT

Why is the second and 4th left alone?

Re: sum over paired observations

natson001 — Tue, 07 Oct 2014 18:56:02 GMT

Because I want them to be there.

Re: sum over paired observations

Reeza — Tue, 07 Oct 2014 19:14:54 GMT

Well if the logic is in your head then I guess you'll have to hard code it. Seems kinda pointless then.

Re: sum over paired observations

PGStats — Tue, 07 Oct 2014 19:40:12 GMT

Strange but simple request... Here goes:

data have;

input obs x;

datalines;

1 5

2 6

3 9

4 8

5 6

6 7

;

data want;

if not end then set have(firstobs=2 rename=x=y) end=end;

set have;

if mod(_n_, 2) = 1 then x = x+y;

keep obs x;

run;

Re: sum over paired observations

natson001 — Tue, 07 Oct 2014 20:01:16 GMT

Straightforward and beautiful! Thanks PG!

Re: sum over paired observations

stat_sas — Tue, 07 Oct 2014 21:04:30 GMT

Another way to do it.

data want;
set have;
if mod(_n_,2) then flag+1;
run;

proc sql;
select obs,case when obs=min(obs) then sum(x) else x end as x from want
group by flag
order by obs;
quit;