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

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

similar_text()中文汉字版

复制代码 代码如下:

          //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; 
     }  

levenshtein()中文汉字版
 

复制代码 代码如下:

          //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              $d[$i1] = array(); 
             $d[$i1][0] = $i1; 
         } 
         for ($i2 = 0; $i2              $d[0][$i2] = $i2; 
         } 
         for ($i1 = 1; $i1              for ($i2 = 1; $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); 
     }  

 
最长公共子序列LCS()
 

复制代码 代码如下:

                  //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              $dp[$i] = array(); 
             $dp[$i][0] = 0; 
             $dp[0][$i] = 0; 
           } 
           for ($i = 1; $i              for ($j = 1; $j                if ($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              $dp[$i] = array(); 
             $dp[$i][0] = 0; 
             $dp[0][$i] = 0; 
           } 
           for ($i = 1; $i              for ($j = 1; $j                if ($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]; 
         }

(100分)[php]写几个你熟悉的字符串处理函数!

addcslashes addslashes bin2hex chop chr chunk_split convert_cyr_string cyrillic
convert_uudecode convert_uuencode count_chars crc32 crc32 crypt echo explode

fprintf get_html_translation_table hebrev

hebrevc
hex2bin — Decodes a hexadecimally encoded binary string
html_entity_decode — Convert all HTML entities to their applicable characters
htmlentities — Convert all applicable characters to HTML entities
htmlspecialchars_decode — Convert special HTML entities back to characters
htmlspecialchars — Convert special characters to HTML entities
implode — Join array elements with a string
join

lcfirst — Make a string's first character lowercase
levenshtein — Calculate Levenshtein distance between two strings
localeconv — Get numeric formatting information
ltrim — Strip whitespace (or other characters) from the beginning of a string
md5_file
metaphone — Calculate the metaphone key of a string
money_format — Formats a number as a currency string
nl_langinfo — Query language and locale information
nl2br

number_format — Format a number with grouped thousands
ord

parse_str

print

printf

quoted_printable_decode — Convert a quoted-printable string to an 8 bit string
quoted_printable_encode — Convert a 8 bit string to a quoted-printable string
quotemeta — Quote meta characters
rtrim
setlocale — Set locale information
sha1_file

sha1

soundex — Calculate the soundex key of a string
sprintf — Return a formatted string
sscanf — Parses input from a string according to a ......余下全文>>
 

对于php的levenshtein函数可以否给个通俗易懂的解释，手册看不懂

W3School的解释：
levenshtein() 函数返回两个字符串之间的 Levenshtein 距离。
Levenshtein 距离，又称编辑距离，指的是两个字符串之间，由一个转换成另一个所需的最少编辑操作次数。许可的编辑操作包括将一个字符替换成另一个字符，插入一个字符，删除一个字符。
例如把 kitten 转换为 sitting：
sitten （k→s）
sittin （e→i）
sitting （→g）
levenshtein() 函数给每个操作（替换、插入和删除）相同的权重。不过，您可以通过设置可选的 insert、replace、delete 参数，来定义每个操作的代价。

说明：“代价”就是权重。楼主的例子中，Hello World→ello World，需要“删除”“H”，也就是采用了第五个参数，对应的权重是30，所以返回30.
 

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