Current File : /home/tjamichg/cursos.tjamich.gob.mx/vendor/graphp/algorithms/src/ShortestPath/BreadthFirst.php
<?php
namespace Graphp\Algorithms\ShortestPath;
use Fhaculty\Graph\Vertex;
use Fhaculty\Graph\Exception\OutOfBoundsException;
use Fhaculty\Graph\Set\Edges;
use Fhaculty\Graph\Set\Vertices;
/**
* Simple breadth-first shortest path algorithm
*
* This algorithm ignores edge weights and operates as a level-order algorithm
* on the number of hops. As such, it considers the path with the least number
* of hops to be shortest.
*
* This is particularly useful your Graph doesn't have Edge weights assigned to
* begin with or if you're merely interested in knowing which Vertices can be
* reached at all (path finding). This avoids running expensive operations to
* determine the actual weight (distance) of a path.
*/
class BreadthFirst extends Base
{
/**
* get distance between start vertex and given end vertex
*
* @param Vertex $endVertex
* @throws OutOfBoundsException if there's no path to given end vertex
* @return float
* @uses self::getEdgesTo()
*/
public function getDistance(Vertex $endVertex)
{
return (float)\count($this->getEdgesTo($endVertex));
}
/**
* get array of edges on the walk for each vertex (vertex ID => array of walk edges)
*
* @return array[]
*/
public function getEdgesMap()
{
$vertexQueue = array();
$edges = array();
// $edges[$this->vertex->getId()] = array();
$vertexCurrent = $this->vertex;
$edgesCurrent = array();
do {
foreach ($vertexCurrent->getEdgesOut() as $edge) {
$vertexTarget = $edge->getVertexToFrom($vertexCurrent);
$vid = $vertexTarget->getId();
if (!isset($edges[$vid])) {
$vertexQueue[] = $vertexTarget;
$edges[$vid] = \array_merge($edgesCurrent, array($edge));
}
}
// get next from queue
$vertexCurrent = \array_shift($vertexQueue);
if ($vertexCurrent) {
$edgesCurrent = $edges[$vertexCurrent->getId()];
}
// untill queue is empty
} while ($vertexCurrent);
return $edges;
}
public function getEdgesTo(Vertex $endVertex)
{
if ($endVertex->getGraph() === $this->vertex->getGraph()) {
$map = $this->getEdgesMap();
if (isset($map[$endVertex->getId()])) {
return new Edges($map[$endVertex->getId()]);
}
}
throw new OutOfBoundsException('Given target vertex can not be reached from start vertex');
}
/**
* get map of vertex IDs to distance
*
* @return float[]
* @uses Vertex::hasLoop()
*/
public function getDistanceMap()
{
$ret = array();
foreach ($this->getEdgesMap() as $vid => $edges) {
$ret[$vid] = (float)\count($edges);
}
return $ret;
}
/**
* get array of all target vertices this vertex has a path to
*
* @return Vertices
* @uses self::getEdgesMap()
*/
public function getVertices()
{
$ret = array();
$graph = $this->vertex->getGraph();
foreach (\array_keys($this->getEdgesMap()) as $vid) {
$ret[$vid] = $graph->getVertex($vid);
}
return new Vertices($ret);
}
public function getEdges()
{
$ret = array();
foreach ($this->getEdgesMap() as $edges) {
foreach ($edges as $edge) {
if (!\in_array($edge, $ret, true)) {
$ret[] = $edge;
}
}
}
return new Edges($ret);
}
}
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