NAME

       Graph::AdjacencyMatrix - create and query the adjacency matrix of graph G

SYNOPSIS

           use Graph::AdjacencyMatrix;
           use Graph::Directed; # or Undirected

           my $g  = Graph::Directed->new;
           $g->add_...(); # build $g

           my $am = Graph::AdjacencyMatrix->new($g);
           $am->is_adjacent($u, $v)

           my $am = Graph::AdjacencyMatrix->new($g, distance_matrix => 1);
           $am->distance($u, $v)

           my $am = Graph::AdjacencyMatrix->new($g, attribute_name => 'length');
           $am->distance($u, $v)

           my $am = Graph::AdjacencyMatrix->new($g, ...);
           my @V  = $am->vertices();

           $g = Graph->new(multiedged => 1);
           $g->add_...(); # build $g
           $am = Graph::AdjacencyMatrix->new($g, distance_matrix => 1);
           $am->distance($u, $v) # returns hash-ref of ID => distance

DESCRIPTION

       You can use "Graph::AdjacencyMatrix" to compute the adjacency matrix and optionally also the distance
       matrix of a graph, and after that query the adjacencyness between vertices by using the "is_adjacent()"
       method, or query the distance between vertices by using the "distance()" method.

       By default the edge attribute used for distance is "w", but you can change that in new(), see below.

       If you modify the graph after creating the adjacency matrix of it, the adjacency matrix and the distance
       matrix may become invalid.

Methods

   Class Methods
       new($g)
           Construct the adjacency matrix of the graph $g.

       new($g, options)
           Construct the adjacency matrix of the graph $g with options as a hash.  The known options are

           distance_matrix => boolean
                   By default only the adjacency matrix is computed.  To compute also the distance matrix, use
                   the attribute "distance_matrix" with a true value to the new() constructor.

           attribute_name => attribute_name
                   By default the edge attribute used for distance is "w".  You can change that by giving
                   another attribute name with the "attribute_name" attribute to new() constructor.  Using this
                   attribute also implicitly causes the distance matrix to be computed.

   Object Methods
       is_adjacent($u, $v)
           Return true if the vertex $v is adjacent to vertex $u, or false if not.

       distance($u, $v)
           Return the distance between the vertices $u and $v, or "undef" if the vertices are not adjacent.

           If the underlying graph is multiedged, returns hash-ref of ID mapped to distance. If a given edge ID
           does not have the attribute defined, it will not be represented. If no edge IDs have the attribute,
           "undef" will be returned.

       adjacency_matrix
           Return the adjacency matrix itself (a list of bitvector scalars).

       vertices
           Return the list of vertices (useful for indexing the adjacency matrix).

ALGORITHM

       The algorithm used to create the matrix is two nested loops, which is O(V**2) in time, and the returned
       matrices are O(V**2) in space.

SEE ALSO

       Graph::TransitiveClosure, Graph::BitMatrix

AUTHOR AND COPYRIGHT

       Jarkko Hietaniemi jhi@iki.fi

LICENSE

       This module is licensed under the same terms as Perl itself.