#
# Rank:
# Returns the sample ranks of the values in a list.
#
#                         Adrian Altenhoff, Feb 19. 2009
#

Rank := proc(a_:list ; order:procedure)
    a := a_; n := length(a);
    orderP := If(assigned(order), order, x->x);
    ind := sort([seq(i,i=1..n)], x->orderP(a[x]));
    rank := CreateArray(1..n);

    v := a[ind[1]]; j := 1; rank[ind[1]] := 1;
    for i from 2 to n do
        if a[ind[i]]=v then next;
        elif (a[ind[i]]<>v and i-j>1) then
            meanval := sum(x,x=j..i-1)/(i-j);
            for k from j to i-1 do rank[ind[k]] := meanval od:
        fi;
        j := i; v:=a[ind[i]]; rank[ind[i]] := i;
    od;

    # fix last ranks if more than one of those element exist.
    if j<>n then
        meanval := sum(x,x=j..n)/(n-j+1);
        for k from j to n do rank[ind[k]] := meanval od:
    fi;

    return(rank);
end: