PageRank的php简单实现

php简单实现PageRank算法

<?php
header("Content-type:text/html; charset=utf-8");

class PageRank
{
    public $map = [];

    public $rank = [];

    public $inputList = []; // example web 'a' (has input link): web 'b'

    public $size;

    public $keyValue = 0.85;

    public function __construct(array $map) {
        $this->map = $map;
        $this->size = count($this->map);
    }

    //init rank score and transform 'map' format to 'inputList' format
    public function init()
    {
        $size = $this->size;
        foreach ($this->map as $key => $value) {
            $this->inputList[$key] = [];
        }
        foreach ($this->map as $key => $value) {
            $this->rank[$key] = 1/$size;
            foreach ($value as $v) {
                if (empty($this->inputList[$v])) {
                    $this->inputList[$v][] = $key;
                } else {
                    array_push($this->inputList[$v], $key);
                }
            }

        }
    }


    public function caculate()
    {
        $tmp = $this->rank;
        $keyValue = $this->keyValue;
        $size = $this->size;

        foreach ($this->inputList as $key => $value) {
            $score = (1 - $keyValue)/$size;
            foreach ($value as $v) {
                $cc = count($this->map[$v]);
                if ($cc) {
                    $score += ($keyValue*(1/$cc * $this->rank[$v]));
                }
            }
            $tmp[$key] = $score;
        }
        $this->rank = $tmp;
    }



}

$map = [
        'a' => ['b', 'c', 'd'],// web 'a' (has out link): web 'b', web 'c', web 'd'
        'b' => ['a', 'd'],
        'c' => ['b'],
        'd' => ['b', 'c'],
];


$example = new PageRank($map);
$example->init();

echo '<pre>';

for ($i = 0; $i < 10; $i++) {
    $example->caculate();
    var_dump($example->rank);
}