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By dave

google_pagerank -- Calculates the Google PageRank of a specified URL

Description

string google_pagerank( string URL )

What is Google PageRank?
PageRank is a family of algorithms for assigning numerical weightings to hyperlinked documents (or web pages) indexed by a search engine. Its properties are much discussed by search engine optimization (SEO) experts. The PageRank system is used by the popular search engine Google to help determine a page's relevance or importance. As Google puts it:

PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page's value. Google interprets a link from page A to page B as a vote, by page A, for page B. But Google looks at more than the sheer volume of votes, or links a page receives; it also analyzes the page that casts the vote. Votes cast by pages that are themselves "important" weigh more heavily and help to make other pages "important."

For more info:
http://www.google.com/corporate/tech.html
http://en.wikipedia.org/wiki/PageRank
http://www.google.com/webmasters/4.html

This function will calculate and return the Google PageRank of the specified input URL as a string.

Example 1. google_pagerank() example

<?php
echo google_pagerank('http://www.nutang.com'); // output: 5
?>

Source Code

<?php

function google_pagerank($url) {

    /* 
    This code is released unto the public domain 
    Raistlin Majere euclide@email.it 
    */

    define('GOOGLE_MAGIC', 0xE6359A60);
    
    //unsigned shift right
    function zeroFill($a, $b)
    {
    $z = hexdec(80000000);
    if ($z & $a)
    {
    $a = ($a>>1);
    $a &= (~$z);
    $a |= 0x40000000;
    $a = ($a>>($b-1));
    }
    else
    {
    $a = ($a>>$b);
    }
    return $a;
    }
    
    function mix($a,$b,$c) {
    $a -= $b; $a -= $c; $a ^= (zeroFill($c,13));
    $b -= $c; $b -= $a; $b ^= ($a<<8);
    $c -= $a; $c -= $b; $c ^= (zeroFill($b,13));
    $a -= $b; $a -= $c; $a ^= (zeroFill($c,12));
    $b -= $c; $b -= $a; $b ^= ($a<<16);
    $c -= $a; $c -= $b; $c ^= (zeroFill($b,5));
    $a -= $b; $a -= $c; $a ^= (zeroFill($c,3)); 
    $b -= $c; $b -= $a; $b ^= ($a<<10);
    $c -= $a; $c -= $b; $c ^= (zeroFill($b,15));
    
    return array($a,$b,$c);
    }
    
    function GoogleCH($url, $length=null, $init=GOOGLE_MAGIC) {
    if(is_null($length)) {
    $length = sizeof($url);
    }
    $a = $b = 0x9E3779B9;
    $c = $init;
    $k = 0;
    $len = $length;
    while($len >= 12) {
    $a += ($url[$k+0] +($url[$k+1]<<8) +($url[$k+2]<<16) +($url[$k+3]<<24));
    $b += ($url[$k+4] +($url[$k+5]<<8) +($url[$k+6]<<16) +($url[$k+7]<<24));
    $c += ($url[$k+8] +($url[$k+9]<<8) +($url[$k+10]<<16)+($url[$k+11]<<24));
    $mix = mix($a,$b,$c);
    $a = $mix[0]; $b = $mix[1]; $c = $mix[2];
    $k += 12;
    $len -= 12;
    }
    
    $c += $length;
    switch($len) /* all the case statements fall through */
    {
    case 11: $c+=($url[$k+10]<<24);
    case 10: $c+=($url[$k+9]<<16);
    case 9 : $c+=($url[$k+8]<<8);
    /* the first byte of c is reserved for the length */
    case 8 : $b+=($url[$k+7]<<24);
    case 7 : $b+=($url[$k+6]<<16);
    case 6 : $b+=($url[$k+5]<<8);
    case 5 : $b+=($url[$k+4]);
    case 4 : $a+=($url[$k+3]<<24);
    case 3 : $a+=($url[$k+2]<<16);
    case 2 : $a+=($url[$k+1]<<8);
    case 1 : $a+=($url[$k+0]);
    /* case 0: nothing left to add */
    }
    $mix = mix($a,$b,$c);
    /*-------------------------------------------- report the result */
    return $mix[2];
    }
    
    //converts a string into an array of integers containing the numeric value of the char
    function strord($string) {
    for($i=0;$i<strlen($string);$i++) {
    $result[$i] = ord($string{$i});
    }
    return $result;
    }
    
    function get_pr($url) {
    $result=array("",-1);
    
    if (($url.""!="")&&($url.""!="http://")):
    // check for protocol 
    if (substr(strtolower($url),0,7)!="http://"):
    $url="http://".$url;
    endif;
    
    $url="info:".$url;
    $checksum=GoogleCH(strord($url));
    $google_url=sprintf("http://www.google.com/search?client=navclient-auto&ch=6%u&features=Rank&q=".$url,$checksum); // url to get from google 
    
    $contents="";
    // let's get ranking 
    // this way could cause problems because the Browser Useragent is not set... 
    if ($handle=fopen($google_url,"rb")):
    while(true):
    $data=fread($handle,8192);
    if (strlen($data)==0):
    break;
    endif;
    $contents.=$data;
    endwhile;
    fclose($handle);
    else:
    $contents="Connection unavailable";
    endif;
    
    $result[0]=$contents;
    // Rank_1:1:0 = 0 
    // Rank_1:1:5 = 5 
    // Rank_1:1:9 = 9 
    // Rank_1:2:10 = 10 etc 
    $p=explode(":",$contents);
    if (isset($p[2])):
    $result[1]=$p[2];
    endif;
    endif;
    
    return $result;
    }
    
    $pr = get_pr($url);
    if($pr[1] == -1)
        $pr[1] = 0;
    return $pr[1];

} // end google_pagerank()

?>

Related Function(s)

site_pageranks()