this code is reading in a 4by4 matrix, ( related to biology ) here is the matrix 

0.95 0.02 0.07 0.07 #A
0.03 0.01 0.06 0.83 #C
0.01 0.02 0.80 0.09 #G
0.01 0.95 0.07 0.01 #T

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my $filepath = "OP.txt";
my $newdata = readdt2($filepath);

sub readdt2 {
  my $ifn = shift; # how does this work
  open(my $IFH, "<$ifn") or die "cannot open file $ifn\n";
  my $line;
  my @nucleotides = ("A","C","G","T");
  my %ret; #why did he name a hash return?? that really confused me
  my @tmp;
  for(my $j=0;$j<4;$j++) {
    $ret{$nucleotides[$j]} = []; #dont understand 
    $line = <$IFH>;
    chomp($line);
    @tmp = split(/\s+/,$line);
    for(my $i=0;$i<=$#tmp;$i++) {
      $ret{$nucleotides[$j]}->[$i]= $tmp[$i] ;  #dont understand 
    }
  }
  close($IFH);
  return(\%ret);
}

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what really threw me off was why did he name a hash $ret which is short for return thanks in advance! P.S. how can i make this code more flexible? say it reads in a matrix with unknown dimensions H, and K

In reply to trouble understanding boss's code by DanielM0412

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