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<?php |
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namespace Graphp\Alg\Shortestpath; |
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use Graphp\GraphInterface; |
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use Graphp\GraphPathInterface; |
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use Graphp\GraphUtils; |
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use Graphp\Vertex\VertexInterface; |
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use Graphp\Path\GraphWalk; |
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use Graphp\Alg\Interfaces\SingleSourcePathsInterface; |
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/** |
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* Class TreeSingleSourcePaths |
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* |
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* @package Graphp\Alg\Shortestpath |
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*/ |
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class TreeSingleSourcePaths implements SingleSourcePathsInterface |
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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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* The source vertex |
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* |
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* @var VertexInterface |
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*/ |
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protected $source; |
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/** |
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* A map which keeps for each target vertex the predecessor edge and the total length of the |
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* shortest path |
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* |
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* @var array |
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*/ |
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protected $map; |
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/** |
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* Construct a new instance |
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* |
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* @param GraphInterface $graph - the graph |
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* @param VertexInterface $source - the source vertex |
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* @param array $map - the map |
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*/ |
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public function __construct(GraphInterface $graph, VertexInterface $source, array $map) |
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{ |
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$this->graph = $graph; |
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$this->source = $source; |
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$this->map = $map; |
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} |
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/** |
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* Get the graph over which this set of paths is defined |
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* |
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* @return GraphInterface |
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*/ |
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public function getGraph(): GraphInterface |
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{ |
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return $this->graph; |
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} |
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/** |
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* Get the single source vertex |
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* |
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* @return GraphInterface |
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*/ |
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public function getSourceVertex(): VertexInterface |
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{ |
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return $this->source; |
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} |
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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 $targetVertex - the target vertex |
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* |
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* @return float |
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*/ |
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public function getWeight(VertexInterface $targetVertex): ?float |
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{ |
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$id = $targetVertex->getHash(); |
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if (array_key_exists($id, $this->map)) { |
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return $this->map[$id][0]; |
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} elseif ($this->source->equals($targetVertex)) { |
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return 0.0; |
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} |
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return INF; |
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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 $targetVertex - the target vertex |
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* |
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* @return null|GraphPathInterface |
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*/ |
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public function getPath(VertexInterface $targetVertex): ?GraphPathInterface |
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{ |
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if ($this->source->equals($targetVertex)) { |
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return GraphWalk::singletonWalk($this->graph, $this->source, 0.0); |
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} |
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$edgeList = []; |
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$cur = $targetVertex; |
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$id = $cur->getHash(); |
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if (!array_key_exists($id, $this->map) || $this->map[$id] == INF) { |
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return null; |
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} |
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$p = $this->map[$id]; |
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$weight = 0.0; |
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while (!is_null($p) && !$cur->equals($this->source)) { |
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$edge = $p[1]; |
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if (is_null($edge)) { |
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break; |
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} |
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array_unshift($edgeList, $edge); |
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$weight += $this->graph->getEdgeWeight($edge); |
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$cur = GraphUtils::getOppositeVertex($this->graph, $edge, $cur); |
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$id = $cur->getHash(); |
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if (!array_key_exists($id, $this->map)) { |
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break; |
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} |
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$p = $this->map[$id]; |
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} |
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return new GraphWalk($this->graph, $this->source, $targetVertex, null, $edgeList, $weight); |
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} |
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} |
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bingo-soft /
graphp
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