php实现PageRank的实例

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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);
}

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