$ perl -e '
> my $tokens = q{32,15,4,72,13,28,14};
> my %code = do{
>    my $i = 0;
>    map { $_ => $i ++ } split m{,}, $tokens;
>    };
> print qq{$_ => $code{ $_ }\n}
>    for sort { $code{ $a } <=> $code{ $b } } keys %code;'
32 => 0
15 => 1
4 => 2
72 => 3
13 => 4
28 => 5
14 => 6
$