my @genes;  # I assume these come from somewhere

  for my $style (qw/ g2d pocus dgp /) {
    my($in, $out) = ($style . "_ranking", $style . "_rankratio");

    # step 1: locate and sort the relevant genes for this ranking style
    my @set = sort { $a->{$in} <=> $b->{$in} } grep $_->{$in}, @genes;

    # step 2: get a count
    my $total = @set;

    # step 3: update the located genes with a rankratio
    for my $index (0 .. $#set) {
      $set[$index]{$out} = ($index + 1) / $total;
    }
  }