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<?php |
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namespace Letournel\PathFinder\Algorithms\TravelingSalesman; |
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use Letournel\PathFinder\AlgorithmTravelingSalesman; |
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use Letournel\PathFinder\Core\NodeGraph; |
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use Letournel\PathFinder\Core\NodeMap; |
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use Letournel\PathFinder\Core\NodePath; |
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class NearestNeighbour implements AlgorithmTravelingSalesman |
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{ |
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/* |
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* For more info see |
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* http://en.wikipedia.org/wiki/Nearest_neighbour_algorithm |
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*/ |
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private |
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$graph; |
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public function setGraph(NodeGraph $graph) |
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{ |
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$this->graph = $graph; |
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} |
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public function computeRoute() |
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{ |
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if(! $this->graph instanceof NodeGraph) |
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{ |
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throw new \RuntimeException('Invalid Graph'); |
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} |
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$vertexes = $this->graph->getVertexes(); |
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if(count($vertexes) <= 2) |
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{ |
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return new NodePath($vertexes); |
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} |
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$vertexFrom = array_shift($vertexes); |
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$vertexTo = null; |
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$pathMap = new NodeMap(); |
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$pathMap->insert($vertexFrom, $vertexTo); |
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while(! empty($vertexes)) |
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{ |
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$minimalVertexTo = null; |
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$minimalEdge = INF; |
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$edges = $this->graph->getEdgesFrom($vertexFrom); |
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foreach($edges as $vertexToId => $edge) |
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{ |
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$vertexTo = $this->graph->getVertex($vertexToId); |
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if(! $pathMap->exists($vertexTo) && $edge < $minimalEdge) |
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{ |
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$minimalVertexTo = $vertexTo; |
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$minimalEdge = $edge; |
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} |
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} |
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$pathMap->insert($minimalVertexTo, $vertexFrom); |
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unset($vertexes[$minimalVertexTo->getId()]); |
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$vertexFrom = $minimalVertexTo; |
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} |
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return new NodePath($pathMap->lookupFrom($vertexFrom)); |
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} |
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} |
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The PSR-2 coding standard requires that all properties in a class have their visibility explicitly declared. If you declare a property using
the property is implicitly global.
To learn more about the PSR-2, please see the PHP-FIG site on the PSR-2.