topic Changing the Value of a Macro Variable in SAS Programming

Changing the Value of a Macro Variable

djbateman — Fri, 14 Jul 2017 17:52:30 GMT

I have tried so many different methods, and I can't find out how to change a part of a value of a macro variable.

My program assigns macro variables (RANGE1 through RANGEn) that contain a range that is used later in a conditional statement. I have a couple of variables that I want to edit. The values are:

(upper(WEIGHT_U)="KG" and WEIGHT not between 137 and 205)
(upper(WEIGHT_U)="LB" and WEIGHT not between 137 and 205)

I need to change "WEIGHT_U" to "WEIGHTU". Below is a snippet of what I am trying to do where &cnt. is the number of range statements previously defined.

%macro vsrange;
   %do i=1 %to &cnt;
      %if %index(%substr(%str(&&range&i.),2,31),WEIGHT_U)>0 %then %do;
         %let &&range&i=%sysfunc(tranwrd(&&range&i.,WEIGHT_U,WEIGHTU));
      %end;
   %end;
%mend vsrange;
%vsrange;

I am sure that there may be issues with the fact that the macro values contain quotes and parentheses. I am trying to fix that in the %index() function. I also can't have more than 32 characters (according to an error message), but I can't subset in the %let statement because that will alter the macro value. It also looks like the %let statement is having a hard time assigning a value to an existing macro variable being referenced with &&. Can anyone see what I should possibly do to make my necessary changes?

Re: Changing the Value of a Macro Variable

WarrenKuhfeld — Fri, 14 Jul 2017 18:24:07 GMT

Why double ampersands? From what you said, you want the macro variable names to start with "range" not some resolved value from some macro variable. It is often a good strategy to program problematic code in simpler terms. This creates 10 macro variables (range1 - range10) with no problem.

%macro x;
   %do i = 1 %to 10;
      %let range&i = &i;
      %end;
   %put _local_;   
   %mend;
%x

Re: Changing the Value of a Macro Variable

djbateman — Fri, 14 Jul 2017 18:26:15 GMT

I kept playing around, and it turns out that using a DATA _NULL_ step will do the trick:

%macro vsrange;
   %do i=1 %to &cnt;
      %if %index(%substr(%str(&&range&i.),2,31),WEIGHT_U)>0 %then %do;
         data _null_;
            call symputx("&&range&i",%sysfunc(tranwrd(&&range&i.,WEIGHT_U,WEIGHTU)));
         run;
      %end;
   %end;
%mend vsrange;
%vsrange;

Re: Changing the Value of a Macro Variable

djbateman — Fri, 14 Jul 2017 18:27:35 GMT

Good point. I could have probably gone that route, but I found another solution. Thank you for your contribution though!