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This sample uses macro logic to determine the number of unique values of a variable (the BY variable) and creates a new data set for each. The resulting data set names will be the BY variable value.
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data _null_;
set test end=eof;
by month;
/* On the first case of the BY-Group, */
/* create a new macro variable VARn */
/* and increment the counter FLAG. */
if first.month then do;
flag+1;
call symput('var'||put(flag,8. -L),month);
end;
/* On the last case of the data set, */
/* create a macro variable to contain */
/* the final value of FLAG. */
if eof then
call symput('tot',put(flag,8. -L));
run;
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Create a macro to generate the new data sets using subset criteria based on the value of the BY variable. This dynamically produces data set names on the DATA statement.
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%macro groups(dsn,byvar);
data %do i=1 %to &tot;
&&var&i;
%end;
set &dsn;
%do i=1 %to &tot;
if &byvar="&&var&i" then output &&var&i;
%end;
run;
%mend groups;
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Call the macro GROUPS and specify the data set name to be split in the first macro parameter and the name of the BY variable in the second parameter.
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%groups(test,month)
proc print data=jan;
title 'January';
run;
proc print data=feb;
title 'February';
run;
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The use of CALL EXECUTE is to pass a parameter to a macro in order to create a new data set for each BY-Group in an existing data set. The output is identical to the output created by Example 1 above. Compile the macro BREAK. The parameter BYVAL will be generated below in the CALL EXECUTE.
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%macro break(byval);
data &byval;
set test(where=(month="&byval"));
run;
%mend;
/* Use the same TEST data set created */
data _null_;
set test;
by month;
if first.month
then call execute('%break('||trim(color)||')');
run;
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