mirror of
https://github.com/Karaka-Management/phpOMS.git
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134 lines
3.3 KiB
PHP
134 lines
3.3 KiB
PHP
<?php
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/**
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* Orange Management
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*
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* PHP Version 8.0
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*
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* @package phpOMS\Business\Marketing
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* @copyright Dennis Eichhorn
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* @license OMS License 1.0
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* @version 1.0.0
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* @link https://orange-management.org
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*/
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declare(strict_types=1);
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namespace phpOMS\Business\Marketing;
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/**
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* PageRank algorithm
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*
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* @package phpOMS\Business\Marketing
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* @license OMS License 1.0
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* @link https://orange-management.org
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* @since 1.0.0
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*/
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final class PageRank
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{
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/**
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* Damping value
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*
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* @var float
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* @since 1.0.0
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*/
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private float $damping = 0.85;
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/**
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* Page rank
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*
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* @var array<mixed, float>
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* @since 1.0.0
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*/
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private array $pageRanks = [];
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/**
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* Relation array
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*
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* Array of elements where every element has an array of incoming links/relations
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*
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* @var array[]
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* @since 1.0.0
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*/
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private array $relations = [];
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/**
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* Amount of outgoing links from an element
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*
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* @var int[]
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* @since 1.0.0
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*/
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private array $outgoing = [];
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/**
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* Constructor.
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*
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* @param array[] $relations Relations between elements (keys => link from, array => link to)
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* @param bool $isUnique Only consider unique relations
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* @param float $damping Damping value
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*
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* @since 1.0.0
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*/
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public function __construct(array $relations, bool $isUnique = true, float $damping = 0.85)
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{
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$this->damping = $damping;
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foreach ($relations as $key => $relation) {
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$this->outgoing[$key] = \count($relation);
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if (!isset($this->relations[$key])) {
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$this->relations[$key] = [];
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}
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foreach ($relation as $linkTo) {
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if (!isset($this->relations[$linkTo])) {
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$this->relations[$linkTo] = [];
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}
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if (!isset($this->outgoing[$linkTo])) {
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$this->outgoing[$linkTo] = 0;
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}
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if (!$isUnique || !\in_array($key, $this->relations[$linkTo])) {
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$this->relations[$linkTo][] = $key;
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}
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}
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}
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}
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/**
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* Calcualte the rank based on a start rank for the different elements
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*
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* A different start rank for different elements might make sense if the elements are not uniform from the very beginning
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*
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* @param int $iterations Algorithm iterations
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* @param null|array<mixed, float> $startRank Start rank for an element
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*
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* @return array
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*
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* @since 1.0.0
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*/
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public function calculateRanks(int $iterations = 20, array $startRank = null) : array
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{
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if ($startRank !== null) {
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$this->pageRanks = $startRank;
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} else {
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foreach ($this->relations as $key => $relation) {
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$this->pageRanks[$key] = 0.0;
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}
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}
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for ($i = 0; $i < $iterations; ++$i) {
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foreach ($this->relations as $key => $relation) {
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$PR = 0.0;
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foreach ($relation as $linkFrom) {
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$PR += $this->pageRanks[$linkFrom] / $this->outgoing[$linkFrom];
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}
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$this->pageRanks[$key] = 1 - $this->damping + $this->damping * $PR;
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}
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}
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return $this->pageRanks;
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}
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}
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