my @labels = ('1', '1', '1', '2', '3', '4', '5', '6', '6', '7'); my @seqs = ('a', 'ctgc', 'tggattgactgtg', 'atgcatg' , 'ctgctgcatgtgatgactgtg', 'tgatg', 'gtgt', 'gcgccggactatgattgagctagcgtatgctgcatgctgat', 'gggtttttttttttccccccccccc', 'aaaaaagggggg'); for $i (0..$#seqs) { $hash{$labels[$i]}.=$seqs[$i]; } print "$hash{$_}\n" for sort keys %hash;