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<?php |
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declare(strict_types=1); |
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namespace drupol\phpermutations\Generators; |
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use drupol\phpermutations\Combinatorics; |
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use drupol\phpermutations\GeneratorInterface; |
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use Generator; |
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use function count; |
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class Permutations extends Combinatorics implements GeneratorInterface |
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{ |
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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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protected $combinations; |
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/** |
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* Permutations constructor. |
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* |
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* @param array<int, mixed> $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 = [], $length = null) |
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{ |
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parent::__construct($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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* {@inheritdoc} |
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*/ |
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public function count(): int |
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{ |
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return $this->combinations->count() * $this->fact($this->getLength()); |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function generator(): Generator |
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{ |
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foreach ($this->combinations->generator() as $combination) { |
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foreach ($this->get($combination) as $current) { |
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yield $current; |
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} |
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} |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function toArray(): array |
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{ |
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$data = []; |
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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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* The permutations generator. |
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* |
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* @param array<int, mixed> $dataset |
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* The dataset |
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* |
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* @return Generator<array> |
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*/ |
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protected function get(array $dataset): Generator |
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{ |
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foreach ($dataset as $key => $firstItem) { |
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$remaining = $dataset; |
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array_splice($remaining, $key, 1); |
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if (0 === count($remaining)) { |
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yield [$firstItem]; |
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continue; |
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} |
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foreach ($this->get($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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drupol /
phpermutations
