I don't think you really want to have the first element be a real array name -- do you have a package named IL12::1 ? If you want to reference these things by name, I suggest (as others have) a hash, with the first element of each row in your file being the key.

Text::CSV_XS would work wonderfully for this application.

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

use IO::File;
use Text::CSV_XS;
use Data::Dumper;

my $io = IO::File->new('myinputfile.txt','<')
   or die "Cannot open input file for reading: $!";

my $csv = Text::CSV_XS->new();

my %data;

while (my $row = $csv->getline($io)) {
   # getline() reads a line from $io and parses it -- fast!
   # $row will contain an ARRAYref, one value for each element

   my $element_name = shift @$row;  #first element is the name
   $data{$element_name} = $row;
}

print Dumper(\%data);  # this will show you how the structure looks
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The output from this should look like:

$VAR1 = {
          'IL12::1::287' => [
                              '6',
                              '-17',
                              '-9',
                              '-21',
                              '-24',
                              '-15',
                              '-2',
                              '11',
                              '4',
                              '4',
                              '-15',
                              '-26',
                              '-16',
                              '-9',
                              '-18',
                              '-25',
                              '27',
                              '17',
                              '6'
                            ]
         ...
        };
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(I've used ... to indicate that there will be more of the same, to save space in this node)

I hope that helps!