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;