table of contents
| Graph::AdjacencyMatrix(3) | User Contributed Perl Documentation | Graph::AdjacencyMatrix(3) |
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.
| 2024-07-01 | perl v5.40.0 |