PageRank的php简单实现

<?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);
}