比较两个字符串的相似度代码,PHP代码库,德仔网

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【PHP】比较两个字符串的相似度
作者:培政 / 发布于2016/7/18/ 667
<?php
/* vim: set expandtab tabstop=4 shiftwidth=4: */
// +----------------------------------------------------------------------+
// | PHP version 5                                                        |
// +----------------------------------------------------------------------+
// | Copyright (c) 1997-2004 The PHP Group                                |
// +----------------------------------------------------------------------+
// | This source file is subject to version 3.0 of the PHP license,       |
// | that is bundled with this package in the file LICENSE, and is        |
// | available through the world-wide-web at the following url:           |
// | http://www.php.net/license/3_0.txt.                                  |
// | If you did not receive a copy of the PHP license and are unable to   |
// | obtain it through the world-wide-web, please send a note to          |
// | license@php.net so we can mail you a copy immediately.               |
// +----------------------------------------------------------------------+
// | Authors: Original Author <author@example.com>                        |
// |          Your Name <you@example.com>                                 |
// +----------------------------------------------------------------------+
//
// $Id:$

class LCS {
   var $str1;
   var $str2;
   var $c = array();
   /*返回串一和串二的最长公共子序列*/
   function getLCS($str1, $str2, $len1 = 0, $len2 = 0) {
      $this->str1 = $str1;
      $this->str2 = $str2;
      if ($len1 == 0) $len1 = strlen($str1);
      if ($len2 == 0) $len2 = strlen($str2);
      $this->initC($len1, $len2);
      return $this->printLCS($this->c, $len1 - 1, $len2 - 1);
   }
   /*返回两个串的相似度
   */
   function getSimilar($str1, $str2) {
      $len1 = strlen($str1);
      $len2 = strlen($str2);
      $len = strlen($this->getLCS($str1, $str2, $len1, $len2));
      return $len * 2 / ($len1 + $len2);
   }
   function initC($len1, $len2) {
      for ($i = 0; $i < $len1; $i++) $this->c[$i][0] = 0;
      for ($j = 0; $j < $len2; $j++) $this->c[0][$j] = 0;
      for ($i = 1; $i < $len1; $i++) {
         for ($j = 1; $j < $len2; $j++) {
            if ($this->str1[$i] == $this->str2[$j]) {
               $this->c[$i][$j] = $this->c[$i - 1][$j - 1] + 1;
            } elseif ($this->c[$i - 1][$j] >= $this->c[$i][$j - 1]) {
               $this->c[$i][$j] = $this->c[$i - 1][$j];
            } else {
               $this->c[$i][$j] = $this->c[$i][$j - 1];
            }
         }
      }
   }
   function printLCS($c, $i, $j) {
      if ($i == 0 || $j == 0) {
         if ($this->str1[$i] == $this->str2[$j]) return $this->str2[$j];
         else return "";
      }
      if ($this->str1[$i] == $this->str2[$j]) {
         return $this->printLCS($this->c, $i - 1, $j - 1).$this->str2[$j];
      } elseif ($this->c[$i - 1][$j] >= $this->c[$i][$j - 1]) {
         return $this->printLCS($this->c, $i - 1, $j);
      } else {
         return $this->printLCS($this->c, $i, $j - 1);
      }
   }
}
$lcs = new LCS();
//返回最长公共子序列
$lcs->getLCS("hello word", "hello china");
//返回相似度
echo $lcs->getSimilar("富平小姐", "白水小姐姐");
?>
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