with(linalg):

polychart:=
[ [`05`,`18`,`26`,`38`,`45`,`54`,`62`,`84`],
[`10`],
[`28`,`06`,`80`],
[`24`,`46`,`85`,`88`],
[`15`,`16`,`23`,`31`,`44`,`61`,`69`,`77`,`83`,`87`,`91`,`95`],
[`02`,`32`],
[`17`,`52`],
[`03`,`09`,`33`,`76`,`82`,`89`],
[`27`,`47`,`66`,`73`,`74`,`81`,`90`],
[`11`],
[`43`],
[`19`,`37`,`48`,`68`],
[`00`,`35`],
[`20`,`36`,`53`,`65`,`97`,`98`],
[`22`,`30`,`34`,`60`,`64`,`67`,`72`],
[`04`,`39`],
[`59`],
[`08`,`56`,`57`,`71`,`79`,`92`],
[`21`,`42`,`49`,`63`,`70`,`94`],
[`12`,`50`,`51`,`55`,`75`,`78`,`86`,`93`,`96`,`99`],
[`29`,`01`,`58`],
[`14`],
[`13`,`25`],
[`41`],
[`40`],
[`07`] ]:

numbers:=proc(s)
        local alph,v,n,m,i,c;
        alph:=`abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ`;
        n:=length(s);
        v:=[];
        for i from 1 to n do
              c:=substring(s,i..i);
              m:=searchtext(c,alph);
              if m > 0 then
                v:=[op(v), (m -1 mod 26) + 1] fi;
        od;
        RETURN(v)
end:

letters:=proc(v)
   local alph,i,msg;
   alph:=`ABCDEFGHIJKLMNOPQRSTUVWXYZ`;
   msg:=``;
   for i from 1 to nops(v) do
       msg:=cat(msg,substring(alph,v[i]..v[i]) );
   od;
   RETURN(msg);
end:

upcase:=w->letters(numbers(w)):

homophoneenc:=proc(s)
    local v,ans,n,i,m,x,randfunc;
    global polychart;
    randfunc:=[seq(rand(1..x), x=1..12)];
    v:=numbers(s);
    n:=nops(v);
    ans:=``;
    for i from 1 to n do
          m:=randfunc[nops(polychart[v[i]])]();
          ans:=cat(ans, polychart[v[i]][m] );
    od;
    RETURN(ans)
end:

homophonedec:=proc(s)
    local alph,v,n,i,c,k,l;
    global polychart;
    alph:=`ABCDEFGHIJKLMNOPQRSTUVWXYZ`;
    n:=length(s);
    v:=``;
    for i from 1 to n/2 do
          c:=substring(s,(2*i-1)..(2*i));
          k:=select(has,polychart,c);
          member(op(k),polychart,'l');
          v:=cat(v, substring(alph,l..l) );
    od;
    RETURN(v)
end:

hfreq:=proc(s)
    local v,n,i,ans,bigram,x,y;
    n:=length(s);
    v:=sort([seq(substring(s,(2*i-1)..(2*i)),i=1..(n/2))]);
    ans:=[];
    bigram:=v[1];
    y:=1;
    for x from 2 to n/2 do
      if v[x] = bigram then
          y:=y+1;
          continue;
      else
          ans:=[op(ans),[bigram,y]];
          bigram:=v[x];
          y:=1;
      fi;
    od;
    ans:=[op(ans),[bigram,y]];
    RETURN(ans)
end:

hfreqsort:=proc(s)
    local A,x,y;
    A:=hfreq(s);
    sort(  A, (x,y)->evalb(x[2]>y[2]))
end:

hpairfreq:=proc(s)
    local v,n,i,ans,bigram,x,y;
    n:=length(s);
    v:=sort([seq(substring(s,(2*i-1)..(2*i+2)),i=1..(n/2)-1)]);
    ans:=[];
    bigram:=v[1];
    y:=1;
    for x from 2 to (n/2)-1 do
      if v[x] = bigram then
          y:=y+1;
          continue;
      else
          ans:=[op(ans),[bigram,y]];
          bigram:=v[x];
          y:=1;
      fi;
    od;
    ans:=[op(ans),[bigram,y]];
    RETURN(ans)
end:

hpairfreqsort:=proc(s)
    local A,x,y;
    A:=hpairfreq(s);
    sort(  A, (x,y)->evalb(x[2]>y[2]))
end:

readin:=proc(filename)
   local fd,q,ans,s;
   fd:=fopen(filename,READ,TEXT);
   q:=fscanf(fd,`%s`);
   ans:=``;
   while q<>0 do
      s:=upcase(op(q));
      ans:=cat(ans,s);
      q:=fscanf(fd,`%s`);
   od;
   fclose(fd);
   RETURN(ans);
end: