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<?php |
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namespace App\Component\Math\Graph\Path; |
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/** |
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* Weighted graph path finder using Floydwarshall method |
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* @author Pierre Fromager <[email protected]> |
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*/ |
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class Floydwarshall |
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{ |
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const INFINITE = 66666; |
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/** |
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* Distances array |
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* @var array |
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*/ |
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protected $dist; |
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/** |
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* Precedence matrix |
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* @var array |
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*/ |
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protected $pred; |
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/** |
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* Weights array |
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* @var array |
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*/ |
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protected $weights; |
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/** |
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* Number of nodes |
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* @var integer |
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*/ |
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protected $nodeCount; |
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/** |
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* Node names list |
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* @var array |
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*/ |
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protected $nodenames; |
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/** |
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* Temporary table for various stuff. |
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* @var array |
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*/ |
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protected $tmp; |
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/** |
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* instanciate |
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* @param array $graph Graph matrice. |
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* @param array $nodenames Node names as an array. |
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*/ |
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public function __construct(array $graph, array $nodenames = []) |
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{ |
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$this->reset(); |
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$this->weights = $graph; |
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$this->nodeCount = count($this->weights); |
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if (!empty($nodenames) && $this->nodeCount == count($nodenames)) { |
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$this->nodenames = $nodenames; |
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} |
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} |
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/** |
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* reset |
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* |
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* @return Floydwarshall |
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*/ |
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1 |
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protected function reset(): Floydwarshall |
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{ |
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1 |
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$this->tmp = []; |
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$this->dist = [[]]; |
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$this->pred = [[]]; |
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return $this; |
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} |
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/** |
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* populate then calculate distance and precedence |
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*/ |
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public function process(): Floydwarshall |
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{ |
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$this->populate(); |
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for ($k = 0; $k < $this->nodeCount; $k++) { |
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for ($i = 0; $i < $this->nodeCount; $i++) { |
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for ($j = 0; $j < $this->nodeCount; $j++) { |
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$nextDist = $this->dist[$i][$k] + $this->dist[$k][$j]; |
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if ($this->dist[$i][$j] > $nextDist) { |
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$this->dist[$i][$j] = $nextDist; |
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$this->pred[$i][$j] = $this->pred[$k][$j]; |
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} |
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} |
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} |
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} |
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return $this; |
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} |
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/** |
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* populate graph nodes to |
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* set distances matrix from weights |
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* and set matrix precedences |
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* |
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* @return Floydwarshall |
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*/ |
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2 |
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protected function populate(): Floydwarshall |
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{ |
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for ($i = 0; $i < $this->nodeCount; $i++) { |
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for ($j = 0; $j < $this->nodeCount; $j++) { |
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if ($i == $j) { |
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$this->dist[$i][$j] = 0; |
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} elseif (isset($this->weights[$i][$j]) && $this->weights[$i][$j] > 0) { |
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$this->dist[$i][$j] = $this->weights[$i][$j]; |
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} else { |
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$this->dist[$i][$j] = self::INFINITE; |
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} |
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$this->pred[$i][$j] = $i; |
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} |
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} |
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return $this; |
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} |
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/** |
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* return distance matrix |
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* |
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* @return array |
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*/ |
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1 |
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public function getDistances(): array |
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{ |
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return $this->dist; |
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} |
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/** |
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* return precedence matrix |
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* |
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* @return array |
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*/ |
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1 |
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public function getPrecedence(): array |
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{ |
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1 |
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return $this->pred; |
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} |
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} |
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pierre-fromager /
nymfonya
