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<?php |
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declare(strict_types=1); |
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namespace KDTree\Search; |
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use KDTree\Interfaces\{KDTreeInterface, NearestSearchInterface, NodeInterface, PointInterface}; |
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final class NearestSearch implements NearestSearchInterface |
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{ |
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/** |
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* @var KDTreeInterface |
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*/ |
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private $tree; |
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/** |
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* @var int |
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*/ |
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private $visited = 0; |
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/** |
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* @var PointInterface|null |
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*/ |
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private $closestPoint; |
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/** |
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* @var float |
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*/ |
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private $bestDistance; |
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/** |
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* @param KDTreeInterface $tree |
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*/ |
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public function __construct(KDTreeInterface $tree) |
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{ |
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$this->tree = $tree; |
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$this->reset(); |
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} |
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/** |
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* @param PointInterface $point |
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* |
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* @return PointInterface|null |
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*/ |
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public function nearest(PointInterface $point): ?PointInterface |
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{ |
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$this->reset(); |
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$this->findNearest($this->tree->getRoot(), $point); |
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return $this->closestPoint; |
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} |
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/** |
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* @return float |
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*/ |
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public function getNearestDistance(): float |
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{ |
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return $this->bestDistance; |
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} |
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/** |
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* @param NodeInterface|null $node |
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* @param PointInterface $searchingPoint |
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* @param int $cuttingDimension |
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*/ |
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private function findNearest(?NodeInterface $node, PointInterface $searchingPoint, int $cuttingDimension = 0): void |
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{ |
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if (null === $node) { |
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return; |
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} |
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++$this->visited; |
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$this->chooseBestDistance($node, $searchingPoint); |
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if (0.0 >= $this->bestDistance) { |
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return; |
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} |
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$dx = $node->getPoint()->getDAxis($cuttingDimension) - $searchingPoint->getDAxis($cuttingDimension); |
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$cuttingDimension = ($cuttingDimension + 1) % $this->tree->getDimensions(); |
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$this->findNearest($dx > 0 ? $node->getLeft() : $node->getRight(), $searchingPoint, $cuttingDimension); |
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if ($dx * $dx >= $this->bestDistance) { |
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return; |
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} |
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$this->findNearest($dx > 0 ? $node->getRight() : $node->getLeft(), $searchingPoint, $cuttingDimension); |
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} |
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private function reset(): void |
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{ |
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$this->bestDistance = (float) PHP_INT_MAX; |
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$this->closestPoint = null; |
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$this->visited = 0; |
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} |
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/** |
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* @param NodeInterface $pretenderNode |
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* @param PointInterface $searchingPoint |
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*/ |
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private function chooseBestDistance(NodeInterface $pretenderNode, PointInterface $searchingPoint): void |
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{ |
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$pretenderDistance = $pretenderNode->getPoint()->distance($searchingPoint); |
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if (null === $this->closestPoint || $pretenderDistance < $this->bestDistance) { |
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$this->bestDistance = $pretenderDistance; |
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$this->closestPoint = $pretenderNode->getPoint(); |
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} |
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} |
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} |
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