my @sequence = ('actg','actg','cggt','cggt');
my @numbers = ('1234','2345','3244','3455');

my (%total, %count, $i);
for ($i=0; $i<@sequence; $i++) {
   $total{$sequence[$i]}+=$numbers[$i];
   $count{$sequence[$i]}++;
}

for (sort keys %total) {
  my $avg=$total{$_}/$count{$_};
  print "$_ avg: $avg\n";
}
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