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<?php |
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/** |
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* Box packing (3D bin packing, knapsack problem) |
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* @package BoxPacker |
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* @author Doug Wright |
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*/ |
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namespace DVDoug\BoxPacker; |
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use Psr\Log\LoggerAwareInterface; |
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use Psr\Log\LoggerAwareTrait; |
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use Psr\Log\LogLevel; |
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use Psr\Log\NullLogger; |
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/** |
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* Actual packer |
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* @author Doug Wright |
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* @package BoxPacker |
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*/ |
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class Packer implements LoggerAwareInterface |
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{ |
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use LoggerAwareTrait; |
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const MAX_BOXES_TO_BALANCE_WEIGHT = 12; |
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/** |
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* List of items to be packed |
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* @var ItemList |
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*/ |
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protected $items; |
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/** |
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* List of box sizes available to pack items into |
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* @var BoxList |
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*/ |
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protected $boxes; |
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/** |
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* Constructor |
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*/ |
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public function __construct() |
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{ |
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$this->items = new ItemList(); |
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$this->boxes = new BoxList(); |
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$this->logger = new NullLogger(); |
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} |
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/** |
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* Add item to be packed |
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* @param Item $item |
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* @param int $qty |
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*/ |
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public function addItem(Item $item, $qty = 1) |
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{ |
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for ($i = 0; $i < $qty; $i++) { |
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$this->items->insert($item); |
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} |
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$this->logger->log(LogLevel::INFO, "added {$qty} x {$item->getDescription()}"); |
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} |
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/** |
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* Set a list of items all at once |
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* @param \Traversable|array $items |
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*/ |
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public function setItems($items) |
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{ |
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if ($items instanceof ItemList) { |
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$this->items = clone $items; |
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} else { |
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$this->items = new ItemList(); |
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foreach ($items as $item) { |
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$this->items->insert($item); |
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} |
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} |
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} |
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/** |
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* Add box size |
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* @param Box $box |
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*/ |
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public function addBox(Box $box) |
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{ |
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$this->boxes->insert($box); |
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$this->logger->log(LogLevel::INFO, "added box {$box->getReference()}"); |
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} |
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/** |
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* Add a pre-prepared set of boxes all at once |
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* @param BoxList $boxList |
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*/ |
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public function setBoxes(BoxList $boxList) |
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{ |
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$this->boxes = clone $boxList; |
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} |
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/** |
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* Pack items into boxes |
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* |
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* @return PackedBoxList |
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*/ |
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public function pack() |
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{ |
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$packedBoxes = $this->doVolumePacking(); |
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//If we have multiple boxes, try and optimise/even-out weight distribution |
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if ($packedBoxes->count() > 1 && $packedBoxes->count() < static::MAX_BOXES_TO_BALANCE_WEIGHT) { |
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$redistributor = new WeightRedistributor($this->boxes); |
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$redistributor->setLogger($this->logger); |
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$packedBoxes = $redistributor->redistributeWeight($packedBoxes); |
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} |
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$this->logger->log(LogLevel::INFO, "packing completed, {$packedBoxes->count()} boxes"); |
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return $packedBoxes; |
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} |
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/** |
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* Pack items into boxes using the principle of largest volume item first |
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* |
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* @throws ItemTooLargeException |
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* @return PackedBoxList |
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*/ |
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public function doVolumePacking() |
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{ |
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$packedBoxes = new PackedBoxList; |
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//Keep going until everything packed |
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while ($this->items->count()) { |
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$boxesToEvaluate = clone $this->boxes; |
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$packedBoxesIteration = new PackedBoxList; |
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//Loop through boxes starting with smallest, see what happens |
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while (!$boxesToEvaluate->isEmpty()) { |
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$box = $boxesToEvaluate->extract(); |
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$volumePacker = new VolumePacker($box, clone $this->items); |
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$volumePacker->setLogger($this->logger); |
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$packedBox = $volumePacker->pack(); |
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if ($packedBox->getItems()->count()) { |
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$packedBoxesIteration->insert($packedBox); |
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//Have we found a single box that contains everything? |
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if ($packedBox->getItems()->count() === $this->items->count()) { |
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break; |
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} |
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} |
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} |
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//Check iteration was productive |
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if ($packedBoxesIteration->isEmpty()) { |
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throw new ItemTooLargeException('Item ' . $this->items->top()->getDescription() . ' is too large to fit into any box', $this->items->top()); |
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} |
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//Find best box of iteration, and remove packed items from unpacked list |
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/** @var PackedBox $bestBox */ |
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$bestBox = $packedBoxesIteration->top(); |
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$unPackedItems = $this->items->asArray(); |
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foreach (clone $bestBox->getItems() as $packedItem) { |
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foreach ($unPackedItems as $unpackedKey => $unpackedItem) { |
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if ($packedItem->getItem() === $unpackedItem) { |
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unset($unPackedItems[$unpackedKey]); |
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break; |
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} |
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} |
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} |
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$unpackedItemList = new ItemList(); |
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foreach ($unPackedItems as $unpackedItem) { |
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$unpackedItemList->insert($unpackedItem); |
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} |
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$this->items = $unpackedItemList; |
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$packedBoxes->insert($bestBox); |
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} |
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return $packedBoxes; |
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} |
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} |
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dvdoug /
BoxPacker
