topic Re: why using 'where' instead of 'if' ? in SAS Programming

why using 'where' instead of 'if' ?

tianerhu — Thu, 19 Aug 2021 15:56:01 GMT

data groups;
set cert.input48;
if upcase(cvar) in ('A','B','C','D','E','F','G') then group=1;
else if upcase(cvar) in ('H','I','J','K','L','M','N') then group=2;
else group=3;
numy=input(y,10.);
run;
proc means data=groups mean maxdec=0;
var numy;
where group=2;
run;

where group=2 , why is not using 'if' ?

Re: why using 'where' instead of 'if' ?

maguiremq — Thu, 19 Aug 2021 16:00:21 GMT

You can't use IF to subset your dataset within PROC MEANS. You can only use WHERE.

In DATA steps, using WHERE on the SET statement usually allows for faster processing by only reading in observations that fit the condition. Using IF requires reading in all observations and then subsetting based on that condition.

Re: why using 'where' instead of 'if' ?

tarheel13 — Thu, 19 Aug 2021 16:29:56 GMT

You can only use if in data step. Proc, you have to use where statement.

Re: why using 'where' instead of 'if' ?

ballardw — Thu, 19 Aug 2021 16:48:31 GMT

@tarheel13 wrote:

You can only use if in data step. Proc, you have to use where statement.

I might modify that "only use IF to subset data in a data step".

A few procedures have places where "IF" is used for things other than subsetting data.

Re: why using 'where' instead of 'if' ?

tianerhu — Thu, 19 Aug 2021 17:52:53 GMT

Thank you for your help.