K-D Tree

PHP multidimensional K-D Tree implementation.

To receive all benefits from K-D Tree, use file system implementation(FSKDTree). FSKDTree stores tree in binary format and uses lazy loading while traversing through nodes. Current approach provides much higher performance compared to deserialization.

Install

Via Composer

$ composer require hexogen/kdtree

Usage

Tree creation

//Item container with 2 dimensional points
$itemList = new ItemList(2);

//Adding 2 - dimension items to the list
$itemList->addItem(new Item(1, [1.2, 4.3]));
$itemList->addItem(new Item(2, [1.3, 3.4]));
$itemList->addItem(new Item(3, [4.5, 1.2]));
$itemList->addItem(new Item(4, [5.2, 3.5]));
$itemList->addItem(new Item(5, [2.1, 3.6]));

//Building tree with given item list
$tree = new KDTree($itemList);

Searching nearest items to the given point

//Creating search engine with custom algorithm (currently Nearest Search)
$searcher = new NearestSearch($tree);

//Retrieving a result ItemInterface[] array with given size (currently 2)
$result = $searcher->search(new Point([1.25, 3.5]), 2);

echo $result[0]->getId(); // 2
echo $result[0]->getNthDimension(0); // 1.3
echo $result[0]->getNthDimension(1); // 3.4

echo $result[1]->getId(); // 1
echo $result[1]->getNthDimension(0); // 1.2
echo $result[1]->getNthDimension(1); // 4.3

Persist tree to a binary file

//Init tree writer
$persister = new FSTreePersister('/path/to/dir');

//Save the tree to /path/to/dir/treeName.bin
$persister->convert($tree, 'treeName.bin');

File system version of the tree

//ItemInterface factory
$itemFactory = new ItemFactory();

//Then init new instance of file system version of the tree
$fsTree = new FSKDTree('/path/to/dir/treeName.bin', $itemFactory);

//Now use fs kdtree to search
$fsSearcher = new NearestSearch($fsTree);

//Retrieving a result ItemInterface[] array with given size (currently 2)
$result = $fsSearcher->search(new Point([1.25, 3.5]), 2);

echo $result[0]->getId(); // 2
echo $result[1]->getId(); // 1

Change log

Please see CHANGELOG for more information on what has changed recently.

Testing

$ composer test

Contributing

Please see CONTRIBUTING and CONDUCT for details.

Security

If you discover any security related issues, please email volodymyrbas@gmail.com instead of using the issue tracker.

Credits

• Volodymyr Basarab
• All Contributors

License

The MIT License (MIT). Please see License File for more information.