#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my @cols = qw(nat pls kac);
my @bigStructure = ();
my $realHeaders;
my $lineCntr = 0;

sub procHeader {
    my $hdrline = shift;
    my @instArray = ();
    my %hash = map {$_=>1} @cols; #thanks kcott
    my @contents = split /\s+/,$hdrline;
    for(@contents)
    {
         if($hash{$_})
         {
	     push @instArray,$_;
          }
         else
         {
	     push @instArray, qw|skip|;
         }         
    }
    return \@instArray;
}

while(<DATA>)
{
    if(!m/^\d/){$realHeaders = procHeader($_)};
    my @row = split /\s+/;
    for (0..$#{$realHeaders})
    {
	if($realHeaders->[$_] ne 'skip')
        {
	    push @{$bigStructure[$lineCntr]}, $row[$_];
        }
    }
    $lineCntr++;
}

    print Dumper \@bigStructure;

1;
__DATA__
nat     pls     fof     tri
0.1     0.1     0.23    0.1
2.3     1.8     3.2     4.4
5.5     3.2     8.6.    7.9

##</code><code>##

$VAR1 = [
          [
            'nat',
            'pls'
          ],
          [
            '0.1',
            '0.1'
          ],
          [
            '2.3',
            '1.8'
          ],
          [
            '5.5',
            '3.2'
          ]
        ];