PHP改进计算字符串相似度的函数similar_text()、levenshtein()

     <?php  
     //拆分字符串  
     function split_str($str) {  
       preg_match_all("/./u", $str, $arr);  
       return $arr[0];  
     }  
       
     //相似度检测  
     function similar_text_cn($str1, $str2) {  
       $arr_1 = array_unique(split_str($str1));  
       $arr_2 = array_unique(split_str($str2));  
       $similarity = count($arr_2) - count(array_diff($arr_2, $arr_1));  
         
       return $similarity;  
     }   

     <?php  
     //拆分字符串  
     function mbStringToArray($string, $encoding = 'UTF-8') {  
         $arrayResult = array();  
         while ($iLen = mb_strlen($string, $encoding)) {  
             array_push($arrayResult, mb_substr($string, 0, 1, $encoding));  
             $string = mb_substr($string, 1, $iLen, $encoding);  
         }  
         return $arrayResult;  
     }  
     //编辑距离  
     function levenshtein_cn($str1, $str2, $costReplace = 1, $encoding = 'UTF-8') {  
         $count_same_letter = 0;  
         $d = array();  
         $mb_len1 = mb_strlen($str1, $encoding);  
         $mb_len2 = mb_strlen($str2, $encoding);  
         $mb_str1 = mbStringToArray($str1, $encoding);  
         $mb_str2 = mbStringToArray($str2, $encoding);  
         for ($i1 = 0; $i1 <= $mb_len1; $i1++) {  
             $d[$i1] = array();  
             $d[$i1][0] = $i1;  
         }  
         for ($i2 = 0; $i2 <= $mb_len2; $i2++) {  
             $d[0][$i2] = $i2;  
         }  
         for ($i1 = 1; $i1 <= $mb_len1; $i1++) {  
             for ($i2 = 1; $i2 <= $mb_len2; $i2++) {  
                 // $cost = ($str1[$i1 - 1] == $str2[$i2 - 1]) ? 0 : 1;  
                 if ($mb_str1[$i1 - 1] === $mb_str2[$i2 - 1]) {  
                     $cost = 0;  
                     $count_same_letter++;  
                 } else {  
                     $cost = $costReplace; //替换  
                 }  
                 $d[$i1][$i2] = min($d[$i1 - 1][$i2] + 1, //插入  
                 $d[$i1][$i2 - 1] + 1, //删除  
                 $d[$i1 - 1][$i2 - 1] + $cost);  
             }  
         }  
         return $d[$mb_len1][$mb_len2];  
         //return array('distance' => $d[$mb_len1][$mb_len2], 'count_same_letter' => $count_same_letter);  
     }   

         <?php  
         //最长公共子序列英文版  
         function LCS_en($str_1, $str_2) {  
           $len_1 = strlen($str_1);  
           $len_2 = strlen($str_2);  
           $len = $len_1 > $len_2 ? $len_1 : $len_2;  
           $dp = array();  
           for ($i = 0; $i <= $len; $i++) {  
             $dp[$i] = array();  
             $dp[$i][0] = 0;  
             $dp[0][$i] = 0;  
           }  
           for ($i = 1; $i <= $len_1; $i++) {  
             for ($j = 1; $j <= $len_2; $j++) {  
               if ($str_1[$i - 1] == $str_2[$j - 1]) {  
                 $dp[$i][$j] = $dp[$i - 1][$j - 1] + 1;  
               } else {  
                 $dp[$i][$j] = $dp[$i - 1][$j] > $dp[$i][$j - 1] ? $dp[$i - 1][$j] : $dp[$i][$j - 1];  
               }  
             }  
           }  
           return $dp[$len_1][$len_2];  
         }  
         //拆分字符串  
         function mbStringToArray($string, $encoding = 'UTF-8') {  
           $arrayResult = array();  
           while ($iLen = mb_strlen($string, $encoding)) {  
             array_push($arrayResult, mb_substr($string, 0, 1, $encoding));  
             $string = mb_substr($string, 1, $iLen, $encoding);  
           }  
           return $arrayResult;  
         }  
         //最长公共子序列中文版  
         function LCS_cn($str1, $str2, $encoding = 'UTF-8') {  
           $mb_len1 = mb_strlen($str1, $encoding);  
           $mb_len2 = mb_strlen($str2, $encoding);  
           $mb_str1 = mbStringToArray($str1, $encoding);  
           $mb_str2 = mbStringToArray($str2, $encoding);  
           $len = $mb_len1 > $mb_len2 ? $mb_len1 : $mb_len2;  
           $dp = array();  
           for ($i = 0; $i <= $len; $i++) {  
             $dp[$i] = array();  
             $dp[$i][0] = 0;  
             $dp[0][$i] = 0;  
           }  
           for ($i = 1; $i <= $mb_len1; $i++) {  
             for ($j = 1; $j <= $mb_len2; $j++) {  
               if ($mb_str1[$i - 1] == $mb_str2[$j - 1]) {  
                 $dp[$i][$j] = $dp[$i - 1][$j - 1] + 1;  
               } else {  
                 $dp[$i][$j] = $dp[$i - 1][$j] > $dp[$i][$j - 1] ? $dp[$i - 1][$j] : $dp[$i][$j - 1];  
               }  
             }  
           }  
           return $dp[$mb_len1][$mb_len2];  
         }