[johngg@justy Documents]$ perl -Mstrict -Mwarnings -MData::Dumper -E '
> my $str = q{BATCATDATEFEAT};
> my %res;
> $res{ $_ } = do {
>    my $ct = 0;
>    my $rhPosns = {};
>    $rhPosns->{ ++ $ct } = pos $str
>       while $str =~ m{$_}g;
>    $rhPosns;
>    } for qw{ A T };
> print Data::Dumper
>    ->new( [ \ %res ], [ qw{ *res } ] )
>    ->Sortkeys( 1 )
>    ->Dumpxs();
> foreach my $let ( sort keys %res )
> {
>     foreach my $seq ( sort { $a <=> $b } keys %{ $res{ $let } } )
>     {
>         say qq{$let=$seq ends at $res{ $let }->{ $seq }};
>     }
> }'
%res = (
         'A' => {
                  '1' => 2,
                  '2' => 5,
                  '3' => 8,
                  '4' => 13
                },
         'T' => {
                  '1' => 3,
                  '2' => 6,
                  '3' => 9,
                  '4' => 14
                }
       );
A=1 ends at 2
A=2 ends at 5
A=3 ends at 8
A=4 ends at 13
T=1 ends at 3
T=2 ends at 6
T=3 ends at 9
T=4 ends at 14
[johngg@justy ~]$