in reply to Re: How do I use Graph::Traversal?
in thread How do I use Graph::Traversal?

Greetings, I'm exploring the Graph::Traversal::DFS in order to compute all possible paths of a directed graph. This solution here: http://www.perlmonks.org/?node_id=382052 Seems to do what I want: provides all paths of a $tree variable as an array of array references. The problem is that the code is too obscure for me understand at the moment and I've already implemented Graph.pm in my code elsewhere and would like to continue using it. All paths shouldn't be a major computational problem in this case because the graphs will be relatively simple and I could get the components first as a simplification. Here's a simple example for a set of vertices called Group 26:

 print qq[$_->{dna}\t$_->{score}\n] foreach @{$RNA_SEQ{$RNA[0]}->{alignments}};

opera_scaffold_55153 28.9909638554217

opera_scaffold_12001 26.5813253012048

opera_scaffold_221202 19.6159638554217

opera_scaffold_220117 15.210843373494

opera_scaffold_184033 1.35542168674699

# The relationship among the vertices is in an array of hash reference called @E. # Each element of @E looks like this: 
{v1 => $vertex1, v2 => $vertex2, rna => $rna, state => 1 }


# build a directed graph with this data, vertices have a weight ( scor
+e )
 
my $g = Graph->new();

for my $edge ( @E )
{
    my %weights = map { $_->{dna} => $_->{score} } @{$RNA_SEQ{$edge->{
+rna}}->{alignments}};
    $g->add_weighted_vertices( $edge->{v1}, $weights{$edge->{v1}}, $ed
+ge->{v2}, $weights{$edge->{v2}});
    $g->add_edge ( $edge->{v1}, $edge->{v2} );
}

# Print out the graph to see what it looks like  

foreach ( @E )
{
    my $w1 = $g->get_vertex_weight($_->{v1});
    my $w2 = $g->get_vertex_weight($_->{v2});
    print qq[$_->{v1} --> $_->{v2}\t$w1 $w2\n];
}

# Output the edges of the graph with weights for each vertex

[download]

opera_scaffold_55153 --> opera_scaffold_221202 28.9909638554217 19.6159638554217

opera_scaffold_221202 --> opera_scaffold_184033 19.6159638554217 1.35542168674699

opera_scaffold_184033 --> opera_scaffold_220117 1.35542168674699 15.210843373494

opera_scaffold_220117 --> opera_scaffold_12001 15.210843373494 26.5813253012048 

# traverse the graph using DFS 
my $t = Graph::Traversal::DFS->new($g);
my @v = $t->preorder;
print qq[Preorder:\n];
print qq[$_\t] foreach @v;

[download]

Preorder: opera_scaffold_221202 opera_scaffold_184033 opera_scaffold_220117 opera_scaffold_12001 opera_scaffold_55153 

@v = $t->postorder;
print qq[Postorder:\n];
print qq[$_\t] foreach @v;

[download]

Postorder: opera_scaffold_12001 opera_scaffold_220117 opera_scaffold_184033 opera_scaffold_221202 opera_scaffold_55153 

my @r = $t->roots;
print qq[Roots:\n];
print qq[$_\t] foreach @r;

[download]

Roots: opera_scaffold_221202 opera_scaffold_55153

Postorder gives me what I want in this example, albeit in the reverse order. However this is a simple example in which the graph has just one single path.

Group 16 looks like this:

Graph Edges:

opera_scaffold_131077 --> opera_scaffold_45770 2.43611177454024 54.8841652734655

opera_scaffold_102945 --> opera_scaffold_23837 13.8762837353714 19.871029376642

Preorder:

opera_scaffold_45770 opera_scaffold_102945 opera_scaffold_23837 opera_scaffold_131077

Postorder:

opera_scaffold_45770 opera_scaffold_23837 opera_scaffold_102945 opera_scaffold_131077

Roots:

opera_scaffold_45770 opera_scaffold_102945 opera_scaffold_131077

Clearly not what I'm looking for. There's two paths in this graph represented by the two edges: opera_scaffold_131077 --> opera_scaffold_45770 and opera_scaffold_102945 --> opera_scaffold_23837 Again, I need a way that, given a graph, I can get back all possible paths. At that point I need to determine the cumulative score for each path, and then choose the one with the highest score. Graph::Traversal seems to offer a lot of options but I'm not sure how to use them all and the documentation isn't very good. Can anyone offer some help on this problem PLEASE. THANKS!.

Replies are listed 'Best First'.
Re^3: How do I use Graph::Traversal?
by Anonymous Monk on Aug 08, 2016 at 02:35 UTC

    o.k that last one was a poor example as I could have computed the components first. The solution is required for other logical possibilities, such as:

    v1 -> v2

    v2 -> v3

    v2 -> v5

    v3 -> v4

    The paths would then be:

    v1 -> v2 ->v3 -> v4

    v1 -> v2 -> v3

[reply]

      Here's my non Graph::Traversal solution. Still looking for something simpler and cleaner with ::Traversal fi someone can help thanks 

      #!/usr/bin/perl -w
use strict;
use warnings;
use diagnostics;
use Graph;
use Graph::Traversal::DFS;


my $g = Graph->new();
$g->add_edges ( ['A', 'B'], ['B', 'C'], ['C', 'D'], ['D', 'K'], ['D', 
+'Z'], ['K', 'R'] );

my @source = $g->source_vertices;

foreach ( @source )
{
    DFS($_);
    print qq[\n\n];
}


sub DFS
{
    my $start_node = shift;
    my @queue = ($start_node);
    my @paths;

    while(scalar(@queue) > 0)
    {
        my $node = pop(@queue);
        my @next_nodes;

        if ( index $node, ':' )
        {
            my @n = split ':', $node;
            my $nnode = $n[-1];
            @next_nodes = $g->successors($nnode);
        }

        else
        {
            @next_nodes = $g->successors($node);
        }

        @next_nodes = map { "$node".':'."$_" } @next_nodes;
        push @paths, $_ foreach @next_nodes;
        push @queue, @next_nodes;
    }

    for my $path ( @paths )
    {
        print qq[$path\n];
    }

}

      [download]

      A:B

      A:B:C

      A:B:C:D

      A:B:C:D:Z

      A:B:C:D:K

      A:B:C:D:K:R

[reply]
[d/l]

        A non redundant set of paths would be better as output if someone can do that, or, given the output as it is above, easily remove the redundant paths.

[reply]
      Can you post runnable code?
[reply]
        #!/usr/bin/perl -w
use strict;
use warnings;
use diagnostics;
use Graph;
use Graph::Traversal::DFS;


my $g = Graph->new();
$graph->add_edges ( ['A', 'B'], ['B', 'C'], ['C', 'D'], ['D', 'K'], ['
+D', 'Z'], ['K', 'R'] );

=some

Path 1: 
A -> B -> C -> D -> K -> R

Path 2:
A -> B -> C -> D -> Z

=cut

my $t = Graph::Traversal::DFS->new($g);
my @v = $t->preorder;
print qq[Preorder:\n];
print qq[$_\t] foreach @v;
print qq[\n];
@v = $t->postorder;
print qq[Postorder:\n];
print qq[$_\t] foreach @v;
print qq[\n];
my @r = $t->roots;
print qq[Roots:\n];
print qq[$_\t] foreach @r;
print qq[\n];

        [download]
[reply]
[d/l]

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