data c1; set sashelp.class; set sashelp.class; run;   data c2;   do i=1 to 2;    set sashelp.class;  end; run;   data c1 is simply a copy of sashelp.class, while dataset c2 contains only the even numbered observations of sashelp.class. Is there anyone please explain the machanism of set statements and why the two programs are different.   Thank you so much!! ... View more

I am trying to split a big data file into several subsets. The subsets only have two repeated observations. Why my code does not work? How come the two duplicated records on each subsets?  Thank you for being so helpful!   options mlogic ; options MPRINT; options SYMBOLGEN; data tt;   do i=1 to 1e7;   KEY = int(ranuni(0)*1e5);   output;   end;   run;     %macro split_1(N=3, data=tt); %do i=1 %to &N;     data or_sub&i;     IF i < &N  THEN  do;   %let   a = %eval(10000*&i);   %let b = %eval(10000+10000*&i);          set tt(FirstObs=&a obs=&b  );    end;      run;  %put ERROR: &i; %end; %mend split_1; %split_1(N=3, data=Tt) ... View more