Current File : /home/tjamichg/cursos.tjamich.gob.mx/vendor/graphp/algorithms/src/MaximumMatching/Flow.php
<?php
namespace Graphp\Algorithms\MaximumMatching;
use Fhaculty\Graph\Exception\UnexpectedValueException;
use Fhaculty\Graph\Set\Edges;
use Fhaculty\Graph\Vertex;
use Graphp\Algorithms\Directed;
use Graphp\Algorithms\Groups;
use Graphp\Algorithms\MaxFlow\EdmondsKarp as MaxFlowEdmondsKarp;
class Flow extends Base
{
public function getEdges()
{
$alg = new Directed($this->graph);
if ($alg->hasDirected()) {
throw new UnexpectedValueException('Input graph contains directed edges');
}
$alg = new Groups($this->graph);
if (!$alg->isBipartit()) {
throw new UnexpectedValueException('Input graph does not have bipartit groups assigned to each vertex. Consider Using "AlgorithmBipartit::createGraph()" first');
}
// create temporary flow graph with supersource and supersink
$graphFlow = $this->graph->createGraphCloneEdgeless();
$superSource = $graphFlow->createVertex();
$superSink = $graphFlow->createVertex();
$groups = $alg->getGroups();
$groupA = $groups[0];
// connect supersource s* to set A and supersink t* to set B
foreach ($graphFlow->getVertices() as $vertex) {
assert($vertex instanceof Vertex);
// we want to skip over supersource & supersink as they do not have a partition assigned
if ($vertex === $superSource || $vertex === $superSink) continue;
$group = $vertex->getGroup();
if ($group === $groupA) {
// group A: source
$superSource->createEdgeTo($vertex)->setCapacity(1)->setFlow(0);
// temporarily create edges from A->B for flow graph
$originalVertex = $this->graph->getVertex($vertex->getId());
foreach ($originalVertex->getVerticesEdgeTo() as $vertexTarget) {
$vertex->createEdgeTo($graphFlow->getVertex($vertexTarget->getId()))->setCapacity(1)->setFlow(0);
}
} else {
// group B: sink
$vertex->createEdgeTo($superSink)->setCapacity(1)->setFlow(0);
}
}
// visualize($resultGraph);
// calculate (s*, t*)-flow
$algMaxFlow = new MaxFlowEdmondsKarp($superSource, $superSink);
$resultGraph = $algMaxFlow->createGraph();
// destroy temporary supersource and supersink again
$resultGraph->getVertex($superSink->getId())->destroy();
$resultGraph->getVertex($superSource->getId())->destroy();
$returnEdges = array();
foreach ($resultGraph->getEdges() as $edge) {
// only keep matched edges
if ($edge->getFlow() > 0) {
$originalEdge = $this->graph->getEdgeClone($edge);
$returnEdges[] = $originalEdge;
}
}
return new Edges($returnEdges);
}
}
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