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<?php declare(strict_types=1); |
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namespace Stratadox\Pathfinder; |
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use Stratadox\Pathfinder\Estimate\Indexed; |
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use Stratadox\Pathfinder\Graph\GeometricView; |
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final class FloydWarshallIndexer implements Indexer |
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{ |
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private $graph; |
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private $shortestPaths; |
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private $distances; |
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public function __construct(Network $network) |
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{ |
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$this->graph = $network; |
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} |
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public static function operatingIn(Network $network): Indexer |
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{ |
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return new self($network); |
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} |
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public function allShortestPaths(): ShortestPathForest |
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{ |
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if (!$this->shortestPaths) { |
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$this->calculateIndex(); |
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} |
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return Index::of($this->shortestPaths); |
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} |
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public function heuristic(): Heuristic |
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{ |
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if (!$this->distances) { |
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$this->calculateIndex(); |
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} |
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return Indexed::heuristic($this->distances, GeometricView::of($this->graph)); |
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} |
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private function calculateIndex(): void |
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{ |
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$dist = []; |
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$next = []; |
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foreach ($this->graph->all() as $node) { |
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$dist[$node][$node] = 0; |
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foreach ($this->graph->neighboursOf($node) as $neighbour) { |
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$dist[$node][$neighbour] = $this->graph->movementCostBetween($node, $neighbour); |
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$next[$node][$neighbour] = $neighbour; |
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} |
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} |
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$all = $this->graph->all()->items(); |
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foreach ($all as $node) { |
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foreach ($all as $start) { |
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$begin = ($dist[$start][$node] ?? INF); |
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foreach ($all as $goal) { |
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$end = ($dist[$node][$goal] ?? INF); |
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$proposition = $begin + $end; |
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$current = ($dist[$start][$goal] ?? INF); |
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if ($proposition < $current) { |
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$dist[$start][$goal] = $dist[$start][$node] + $dist[$node][$goal]; |
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$next[$start][$goal] = $next[$start][$node] ?? null; |
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} |
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} |
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} |
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} |
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$this->distances = $dist; |
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$this->shortestPaths = $next; |
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} |
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} |
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Stratadox /
Pathfinder
