#open file to write filtered lines to
open (OUT2, ">$pos_two") or die "cannot open $pos_two ";
#open file to filter
open (IN2, "<$posfile") or die "cannot open $posfile ";

while (<IN2>) {
  chomp(my $line = $_);
  if ($line =~ m/(comp\d+_c\d+_seq\d+),.+/) {
    my $comp = $1;

    if (grep (/$comp/, @isos20)) {
              
      print OUT2 "$line\n";
    }
    
  }
}

close IN2;
close OUT2;