my($other_array) = ''; foreach $other_array (@other_array){ foreach my$arr (@AoA){ foreach my$sca (@$arr){ $sca if (($sca =~ m/\w+/g)[0] eq ($uniq_kmers =~ m/\w+/g)[0]){ $uniq_kmers =~ "\t".($sca =~ m/\w+/g)[1]; }else{ $uniq_kmers =~ "\t0"; } } } }