if I want column 1 entries to go in one array , second column entry to another and so on . How can i define my array

use strict;
use warnings;
use Data::Dumper;

my $ncols = 5; # or obtained from user
my @bigfatarray = ();
push @bigfatarray, [] for [1 .. $ncols];
while (<DATA>) {
    my @cols = split (/,/, $_);
     for my $i (0 .. $ncols - 1) {
          push @{$bigfatarray[$i]}, $cols[$i];
      }
}
print Dumper (\@bigfatarray);
exit;
__DATA__
1,2,3,4,5
a,b,c,d,e
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Obviously, you'll need to do more than just split your inputs but this should serve as an illustration.