#!/usr/bin/perl -w
use strict;
use Tree::DAG_Node;

my @array = (
    [ 'a', 'b', 'c' ],
    [ 1, 2 ],
    ['x', 'y', 'z'],
    [7, 8, 9]
);

my $tree = Tree::DAG_Node->new;
$tree->name('cols');

sub add_values {
    my $top = shift;
    my $matrix = shift;
    my $level = shift;
    return if $level > $#$matrix;
    my $values = $array[$level];
    $top->new_daughter->name($_) for @$values;
    add_values($_, $matrix, $level+1) for $top->daughters;
}

add_values($tree, \@array, 0);

$tree->walk_down ({
    callbackback => sub {
        my $node = shift;
        print join ( "", reverse map {$_->name}
            grep {$_->address ne '0'}
            $node, $node->ancestors)," ";
    }
});
print "\n";

__END__
a1x7 a1x8 a1x9   a1x   a1y7 a1y8 a1y9   a1y   a1z7 a1z8 a1z9   a1z a1
a2x7 a2x8 a2x9   a2x   a2y7 a2y8 a2y9   a2y   a2z7 a2z8 a2z9   a2z a2 a
b1x7 b1x8 b1x9   b1x   b1y7 b1y8 b1y9   b1y   b1z7 b1z8 b1z9   b1z b1
b2x7 b2x8 b2x9   b2x   b2y7 b2y8 b2y9   b2y   b2z7 b2z8 b2z9   b2z b2 b
c1x7 c1x8 c1x9   c1x   c1y7 c1y8 c1y9   c1y   c1z7 c1z8 c1z9   c1z c1
c2x7 c2x8 c2x9   c2x   c2y7 c2y8 c2y9   c2y   c2z7 c2z8 c2z9   c2z c2 c