use warnings;
use strict;

open my $data, '<', 'alldata.txt'
    or die "Could not open 'alldata.txt': $!\n";

my %dataset;

RECORD:
while ( my $line = <$data> ) {
    chomp $line;
    next RECORD
      unless $line =~ m{\d};
    my ( $coord, $dist, $chr, $exons, $pals ) = split /\s+/, $line;
    next RECORD
       if      exists $dataset{$coord} 
          and $dataset{$coord}{dist} < $dist;

    $dataset{$coord} = { dist        => $dist,
                         chr         => $chr,
                         exons       => $exons,
                         palindromes => $pals,
                       };
}

say "coord\tdist\tchr\texons\tpalindromes";


say "$_\t$dataset{$_}{dist}\t$dataset{$_}{chr}\t$dataset{$_}{exons}\t"
  . "$dataset{$_}{palindromes} "
    for sort { $a <=>  $b } keys %dataset;

##</code><code>##

$VAR1 = {
          '6700' => {
                      'palindromes' => '4',
                      'chr' => '13',
                      'exons' => '1',
                      'dist' => 50
                    },
          '4678' => {
                      'palindromes' => '0',
                      'chr' => '6',
                      'exons' => '2',
                      'dist' => '45'
                    },
          '2346' => {
                      'palindromes' => '567',
                      'chr' => '12',
                      'exons' => '1',
                      'dist' => '78'
                    },
          '5349' => {
                      'palindromes' => '14',
                      'chr' => '8',
                      'exons' => '2',
                      'dist' => '6'
                    },
          '3456' => {
                      'palindromes' => '5',
                      'chr' => '10',
                      'exons' => '1',
                      'dist' => 67
                    },
          '567' => {
                     'palindromes' => '8',
                     'chr' => '5',
                     'exons' => '7',
                     'dist' => '344'
                   },
          '1345' => {
                      'palindromes' => '123',
                      'chr' => '5',
                      'exons' => '8',
                      'dist' => '567'
                    },
          '8964' => {
                      'palindromes' => '8',
                      'chr' => '2',
                      'exons' => '18',
                      'dist' => '560'
                    }
        };