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<?php |
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namespace Graphp\Alg\Shortestpath; |
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use InvalidArgumentException; |
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use Graphp\GraphPathInterface; |
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use Graphp\GraphInterface; |
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use Graphp\Vertex\VertexInterface; |
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use Graphp\Path\GraphWalk; |
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use Graphp\Alg\Interfaces\ShortestPathAlgorithmInterface; |
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use Graphp\Alg\Interfaces\SingleSourcePathsInterface; |
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/** |
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* Class AbstractShortestPathAlgorithm |
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* |
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* @package Graphp\Alg\Shortestpath |
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*/ |
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abstract class AbstractShortestPathAlgorithm implements ShortestPathAlgorithmInterface |
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{ |
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/** |
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* The graph |
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* |
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* @var GraphInterface |
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*/ |
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protected $graph; |
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/** |
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* Construct a new instance of the algorithm for the given graph |
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* |
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* @param GraphInterface $graph - the graph |
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*/ |
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public function __construct(GraphInterface $graph) |
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{ |
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$this->graph = $graph; |
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} |
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/** |
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* Compute all shortest paths starting from a single source vertex. |
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* |
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* @param VertexInterface $sourceVertex - the source vertex |
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* |
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* @return SingleSourcePathsInterface |
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*/ |
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public function getPaths(VertexInterface $source): SingleSourcePathsInterface |
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{ |
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if (!$this->graph->containsVertex($source)) { |
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throw new InvalidArgumentException("graph must contain the source vertex"); |
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} |
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$paths = []; |
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$vertices = $this->graph->vertexSet(); |
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foreach ($vertices as $vertex) { |
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$paths[$vertex->getHash()] = $this->getPath($source, $vertex); |
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} |
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return new ListSingleSourcePaths($this->graph, $source, $paths); |
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} |
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/** |
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* Get the path from the source vertex to the target vertex |
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* |
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* @param VertexInterface $source - the source vertex |
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* @param VertexInterface $sink - the target vertex |
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* |
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* @return null|GraphPathInterface |
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*/ |
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abstract public function getPath(VertexInterface $source, VertexInterface $sink): ?GraphPathInterface; |
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/** |
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* Get the weight of the path from the source vertex to the target vertex. |
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* |
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* @param VertexInterface $sourceVertex - the source vertex |
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* @param VertexInterface $targetVertex - the target vertex |
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* |
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* @return float |
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*/ |
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public function getPathWeight(VertexInterface $source, VertexInterface $sink): float |
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{ |
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$p = $this->getPath($source, $sink); |
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if (is_null($p)) { |
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return INF; |
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} |
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return $p->getWeight(); |
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} |
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/** |
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* Create emppty path from the source vertex to the target vertex. |
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* |
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* @param VertexInterface $sourceVertex - the source vertex |
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* @param VertexInterface $targetVertex - the target vertex |
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* |
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* @return null|GraphPathInterface |
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*/ |
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protected function createEmptyPath(VertexInterface $source, VertexInterface $sink): ?GraphPathInterface |
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{ |
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if ($source->equals($sink)) { |
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return GraphWalk::singletonWalk($this->graph, $source, 0.0); |
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} |
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return null; |
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} |
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} |
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bingo-soft /
graphp
