open (TXT, "<$filename") || die "Can't open $filename: $!\n";
my @array;

while (my $line=<TXT>) {
    chomp($line);
    my @list = split /,/, $line;
    # now distribute the elements into each column's array
    for ( 0 .. $#list ) {
        push @{$array[$_]}, $list[$_];
    }
}