* Union Example
  Form the union of two datasets using (1) stacking and 
  (2) interleaving;

options ls=64 nodate pageno=1;
data coarse;
   infile 'c:/datasets/bolts-coarse.txt' firstobs=2;
   input cat_no $ size diam length price;

data fine;
   infile 'c:/datasets/bolts-fine.txt' firstobs=2;
   input cat_no $ size diam length price;

proc print data=coarse;

proc print data=fine;

data stack;
   set coarse (in=coarse) fine (in=fine);
   if coarse then type='coarse';
   if fine then type='fine';

proc print data=stack;

data interleave;
   set coarse (in=coarse) fine (in=fine);
      by cat_no;
   if coarse then type='coarse';
   if fine then type='fine';

proc print data=interleave;

run;
quit;