#!/usr/bin/perl 
use warnings;
use strict;

use Data::Dumper;

my $filepath = "OP.txt";
my $olddata = readdt2($filepath);
print Dumper($olddata);

sub readdt2 {
  my $ifn = shift;
  open(my $IFH, "<$ifn") or die "cannot open file $ifn\n";
  my $line;
  my @nt = qw(A C T G);
  my @ret;
  my @tmp;
  for (my $j=0; $j<=$#tmp; $j++) {
    $ret[$nt[$j]] = [];
    $line = <$IFH>;
    chomp($line);
    @tmp = split(/\s+/,$line);
    for (my $i=0;$i<=$#tmp;$i++) {
      $ret[$nt[$j]][$i]= $tmp[$i] +0.0001;
    }
  }
  close($IFH);
  return(\@ret);
}