Current File : /home/tjamichg/cursos.tjamich.gob.mx/vendor/graphp/algorithms/src/Symmetric.php
<?php
namespace Graphp\Algorithms;
use Fhaculty\Graph\Edge\Directed as EdgeDirected;
/**
* Basic algorithms for working with symmetric digraphs
*
* A directed graph is called symmetric if, for every arc that belongs to it,
* the corresponding reversed arc (antiparallel directed edge) also belongs to it.
*
* @link http://en.wikipedia.org/wiki/Directed_graph#Classes_of_digraphs
*/
class Symmetric extends BaseGraph
{
/**
* checks whether this graph is symmetric (for every edge a->b there's also an edge b->a)
*
* @return bool
* @uses Graph::getEdges()
* @uses EdgeDirected::getVertexStart()
* @uses EdgeDirected::getVertedEnd()
* @uses Vertex::hasEdgeTo()
*/
public function isSymmetric()
{
// check all edges
foreach ($this->graph->getEdges() as $edge) {
// only check directed edges (undirected ones are symmetric by definition)
if ($edge instanceof EdgeDirected) {
// check if end also has an edge to start
if (!$edge->getVertexEnd()->hasEdgeTo($edge->getVertexStart())) {
return false;
}
}
}
return true;
}
}
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