Numeric values and intervals in SAS Macro Programming

[#1]

You may already know the use of the MINOPERATOR and MINDELIMITER in the SAS Macro Language. This gives us the flexibility to write code using the IN operator a la in the DATA step. Intervals are not allowed however.

An alternative approach is using a handy little SAS macro ISINLIST:

%macro IsInList(value,list);
    %local i j listElement listElements start finish;

    %if %sysfunc(notdigit(&value)) %then %do;
        %put ERROR: (IsInList) Macro variable value is not numeric.;
        0
        %return;
    %end;
    %if &list= %then %do;
        %put ERROR: (IsInList) List is empty;
        0
        %return;
    %end;

    %if %sysfunc(notdigit(%sysfunc(compress(&list,%str( :))))) %then %do;
        %put ERROR: (IsInList) List can only be numbers and intervals;
        0
        %return;
    %end;

    %let listElements=%sysfunc(countw(&list,%str( )));

    %do i=1 %to &listelements;
        %let listElement=%scan(&list,&i,%str( ));
        %if %index(&listElement,%str(:)) %then %do;
            %let start=%scan(&listElement,1,%str(:));
            %let finish= %scan(&listElement,2,%str(:));
            %if &start ge &finish %then %do;
                %put ERROR: (IsInList) Interval error "&listelement": Start must be < finish;
                0 
                %return;
            %end; 
            %do j=&start %to &finish;
                %if &value=&j %then %do;
                    1
                    %return;
                %end;
            %end;
        %end;
        %else %do;
            %if &value=&listelement %then %do;
                1
                %return;
            %end;
        %end;
    %end;
    0
%mend;

Now we can write code like this:

/* do something if MONTH is NOT 1-12 */
%if not %IsInList(&month,1:12) %then...

/* do something if MONTH is 1-12 */
%if %IsInList(&month,1:12) %then ...

/* values combined with interval */
%if %IsInList(&code,7 9 13 15:19) %then ...

The first parameter is a reference to a macro variable.

The second parameter is a list of values and/or intervals. Values are separated by a space and intervals has the form START:END.

Please feel free to use and modify the macro as you like.

Have a nice summer out there 😉