/* (Centered) Moving Median */
new; cls;
let data[50,1]=
      60
      61
      60
      62
      60
      63
      64
      65
      69
      70
      69
      66
      64
      64
      62
      64
      65
      55
      53
      57
      60
      58
      63
      63
      63
      68
      69
      69
      68
      69
      70
      67
      66
      67
      68
      69
      69
      77
      80
      80
      78
      76
      76
      72
      71
      70
      73
      71
      78
      80
;
data=rev(data);               /* original data in reverse order */
t=seqa(1,1,rows(data));

library pgraph;
_pltype=6;
_plegctl=1;
_plegstr="actual\000CMMed(5)";
title("(Centered) Moving Median");
xy(t,data~cmmed(data,5));




proc cmmed(x,k);
   local m,i;
   if k%2==0;
      errorlog "ERROR: Parameter k must be odd number.";
      retp(".");
   endif;
   m=zeros(rows(x),cols(x));
   i=(k-1)/2+1;
   do while i<=rows(x)-(k-1)/2;
      m[i,.]=median(x[i-(k-1)/2:i+(k-1)/2,.])';
      i=i+1;
   endo;
   m[1:(k-1)/2,.]=miss(m[1:(k-1)/2,.],0);
   m[rows(x)-(k-1)/2+1:rows(x),.]=miss(m[rows(x)-(k-1)/2+1:rows(x),.],0);
   retp(m);
endp;