PHP improves the functions similar_text() and levenshtein() for calculating string similarity, levenshtein

similar_text() Chinese character version

Copy code The code is as follows:

//Split string
Function split_str($str) {
Preg_match_all("/./u", $str, $arr);
Return $arr[0];
}

//Similarity detection
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() Chinese character version

Copy code The code is as follows:

          //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);
     }

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 <= $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;
                                                                                                       $dp[$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 points)[php]Write a few string processing functions you are familiar with!

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 — De codes 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 .. ....The rest of the text>>

Can you give an easy-to-understand explanation for the levenshtein function of php? I can’t understand the manual

W3School’s explanation:

levenshtein() function returns the Levenshtein distance between two strings.

Levenshtein distance, also known as edit distance, refers to the minimum number of edit operations required between two strings to convert one into the other. Permitted editing operations include replacing one character with another, inserting a character, and deleting a character.

For example, convert kitten to sitting:

sitten (k→s)
sittin (e→i)
sitting (→g)
levenshtein() function gives each operation (replacement, Insertions and deletions) have the same weight. However, you can define the cost of each operation by setting the optional insert, replace, and delete parameters.

Explanation: "Cost" is the weight. In the poster's example, Hello World → ello World, you need to "delete" "H", that is, the fifth parameter is used, and the corresponding weight is 30, so 30 is returned.

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