Date: Mon, 19 Jul 2004 10:55:32 -0400
Reply-To: "Lustig, Roger" <roger.lustig@CITIGROUP.COM>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: "Lustig, Roger" <roger.lustig@CITIGROUP.COM>
Subject: Re: creating a scalar variable
Content-Type: text/plain; charset="iso-8859-1"
Zio:
SAS-L is the mailing-list version of this newsgroup.
SAS *processes* row-by-row. That doesn't mean you can't have a scalar available to your program.
More precisely, SAS does its processing on a "program data vector" or PDV, which contains everything needed to process the current row.
RETAIN leaves a variable in the PDV. DROP keeps a variable from being output to the data set(s) referenced in the DATA statement. So, if you RETAIN and then DROP a variable, it will be available during processing, but won't show up in the data set itself.
Now, how to get the variable in there? One way:
data new(drop=scalar_val);
set old;
if _N_=1 then set scalar;
<more code>;
run;
This assumes that you have a 1x1 (well, 1-row--you might have several scalars) table called SCALAR out there. You don't even need the RETAIN here, because variables read in from a SET statement are RETAINed automatically.
Then there are macro variables. If your scalar is an integer, or if high precision isn't needed, this is easy.
proc sql;
select max(salary) into :max_salary from master.employ;
quit;
data new;
set old;
if new_salary >= &max_salary then do;
<etc.>
end;
run;
Note the colon prefix in the INTO clause in the SQL query. That makes a macro variable. Note that, when the macro variable is resolved, you'll be comparing NEW_SALARY to a constant.
You can also create/populate the macro variable by using CALL SYMPUT in a DATA step.
To sum up:
--SAS steps (DATA and PROC) create and/or operate on tables.
--Outside of these steps, global macro variables may be kept and manipulated.
--*You* can use these tools to get scalars or their equivalent to the places where you want them to be.
Roger
-----Original Message-----
From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU]On Behalf Of Zio
Fester
Sent: Monday, July 19, 2004 10:05 AM
To: SAS-L@LISTSERV.UGA.EDU
Subject: Re: creating a scalar variable
In article <446DDE75CFC7E1438061462F85557B0F027E6C68
@remail2.westat.com>, HERMANS1@WESTAT.COM says...
> Zio:
> I hope that your instructor doesn't subscribe to SAS-L!
Please forgive my ignorance, but what does that happen to be?
> Whatever his or her
> skill level, it does turn out that SAS, like many other so-called 'database
> programming languages', operates on actual or virtual tables. A table can
> degenerate to a one-column, one-row cell that has many of the properties of
> a scalar. More typically, a database programmer combines tabular datasets to
> produce solutions to programming problems.
Does this mean that SAS can only "think" row by row and that there's no
way to create a scalar variable (or a 1x1 matrix...) accessible from any
part of my code?
> It takes a while to learn how to combine tabular datasets effectively. Once
> you learn how, you will be able to do more in less time and with fewer
> errors.
> Sig
