Merging macros

%stdmerge you have already met. The others just have varying ``if'' conditions.

• %kbmerge: ``Keep both'' merge keeps an observation if it is in either of the input datasets. In addition, it creates variables that tell you which dataset an observation came from:

  %macro kbmerge(inds1, inds2, byvar, outds);
      proc sort data=&inds1 nothreads;
  			      by &byvar;
          
      proc sort data=&inds2 nothreads;
          by &byvar;
      
      data &outds;
          merge &inds1(in=a) &inds2(in=b);
          by &byvar;
          if a or b;
          in&inds1=a;
          in&inds2=b;
      run;
  %mend;
     

• %kfmerge: ``keep first'' merge keeps only observations from the first dataset. This is just %stdmerge with the ``if'' line replaced.

  %macro kfmerge(inds1, inds2, byvar, outds);
      proc sort data=&inds1 nothreads;
          by &byvar;
          
      proc sort data=&inds2 nothreads;
          by &byvar;
      
      data &outds;
          merge &inds1(in=a) &inds2(in=b);
          by &byvar;
          if a;
      run;
  %mend;
  

• %rmsecmerge: ``remove second'' merge removes the observations from the first dataset that occur in the second. The only difference again is the if line:

  %macro rmsecmerge(inds1, inds2, byvar, outds);
      proc sort data=&inds1 nothreads;
          by &byvar;
          
      proc sort data=&inds2 nothreads;
          by &byvar;
      
      data &outds;
          merge &inds1(in=a) &inds2(in=b);
          by &byvar;
          if not b;
      run;
  %mend;