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<?php |
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namespace drupol\phpermutations\Generators; |
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use drupol\phpermutations\Combinatorics; |
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/** |
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* Class Permutations. |
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* |
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* @package drupol\phpermutations\Generators |
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* |
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* Inspired by the work of Mark Wilson <[email protected]> |
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*/ |
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class Permutations extends Combinatorics { |
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/** |
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* The combinations generator. |
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* |
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* @var \drupol\phpermutations\Generators\Combinations |
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*/ |
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public $combinations; |
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/** |
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* Combinatorics constructor. |
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* |
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* @param array $dataset |
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* The dataset. |
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* @param int|null $length |
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* The length. |
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*/ |
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public function __construct(array $dataset = array(), $length = NULL) { |
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parent::__construct($dataset, $length); |
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$this->combinations = new Combinations($dataset, $this->getLength()); |
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} |
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/** |
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* Alias of the get() method. |
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* |
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* @return \Generator |
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* The prime generator. |
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*/ |
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public function generator() { |
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return $this->get($this->getDataset(), $this->getLength()); |
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} |
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/** |
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* The combination generator. |
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* |
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* @param array $dataset |
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* The dataset. |
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* @param int $length |
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* The length. |
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* |
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* @codingStandardsIgnoreStart |
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* @return \Generator |
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* @codingStandardsIgnoreEnd |
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*/ |
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protected function get(array $dataset, $length) { |
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foreach ($this->combinations->generator() as $combination) { |
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foreach ($this->getPermutations($combination) as $current) { |
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yield $current; |
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} |
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} |
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} |
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/** |
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* The permutations generator. |
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* |
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* @param array $dataset |
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* The dataset. |
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* |
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* @codingStandardsIgnoreStart |
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* @return \Generator |
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* @codingStandardsIgnoreEnd |
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*/ |
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protected function getPermutations(array $dataset) { |
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foreach ($dataset as $key => $firstItem) { |
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$remaining = $dataset; |
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array_splice($remaining, $key, 1); |
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if (count($remaining) === 0) { |
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yield [$firstItem]; |
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continue; |
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} |
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foreach ($this->getPermutations($remaining) as $permutation) { |
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array_unshift($permutation, $firstItem); |
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yield $permutation; |
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} |
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} |
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} |
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/** |
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* Convert the generator into an array. |
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* |
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* @return array |
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* The elements. |
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*/ |
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public function toArray() { |
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$data = array(); |
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foreach ($this->generator() as $value) { |
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$data[] = $value; |
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} |
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return $data; |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function count() { |
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return $this->combinations->count() * $this->fact($this->getLength()); |
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} |
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} |
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drupol /
phpermutations
