问题描述
如果我在 mysql 中有两个字符串:
<前>@a="欢迎使用堆栈溢出"@b="你好堆栈溢出";有没有办法使用 MYSQL 获得这两个字符串之间的相似度百分比?例如，这里有 3 个词是相似的，因此相似度应该是这样的:
count(@a 和@b 之间的相似词)/(count(@a)+count(@b) - count(intersection))
因此结果是 3/(4 + 4 - 3)= 0.6
任何想法都受到高度赞赏！
你可以使用这个功能(cop^H^H^Hadapted from http://www.artfulsoftware.com/infotree/queries.php#552):
CREATE FUNCTION `levenshtein`( s1 text, s2 text) 返回 int(11)确定性开始声明 s1_len, s2_len, i, j, c, c_temp, cost INT;声明 s1_char CHAR;声明 cv0、cv1 文本；SET s1_len = CHAR_LENGTH(s1), s2_len = CHAR_LENGTH(s2), cv1 = 0x00, j = 1, i = 1, c = 0;如果 s1 = s2 那么返回 0;ELSEIF s1_len = 0 那么返回 s2_len;ELSEIF s2_len = 0 那么返回 s1_len;别的当 j <= s2_len 时SET cv1 = CONCAT(cv1, UNHEX(HEX(j))), j = j + 1;结束时；当 i <= s1_len 时SET s1_char = SUBSTRING(s1, i, 1), c = i, cv0 = UNHEX(HEX(i)), j = 1;当 j <= s2_len 时SET c = c + 1;如果 s1_char = SUBSTRING(s2, j, 1) THEN设置成本 = 0;ELSE SET 成本 = 1;万一;SET c_temp = CONV(HEX(SUBSTRING(cv1, j, 1)), 16, 10) + 成本；如果 c >c_temp THEN SET c = c_temp;万一;SET c_temp = CONV(HEX(SUBSTRING(cv1, j+1, 1)), 16, 10) + 1;如果 c >c_temp THENSET c = c_temp;万一;SET cv0 = CONCAT(cv0, UNHEX(HEX(c))), j = j + 1;结束时；设置 cv1 = cv0, i = i + 1;结束时；万一;返回 c;结尾为了获得 XX% 使用这个函数
CREATE FUNCTION `levenshtein_ratio`( s1 text, s2 text ) 返回 int(11)确定性开始声明 s1_len、s2_len、max_len INT；设置 s1_len = LENGTH(s1), s2_len = LENGTH(s2);如果 s1_len >s2_len 那么设置 max_len = s1_len;别的设置 max_len = s2_len;万一;返回 ((1 - LEVENSHTEIN(s1, s2)/max_len) * 100);结尾if i have two strings in mysql:
@a="Welcome to Stack Overflow" @b=" Hello to stack overflow";
is there a way to get the similarity percentage between those two string using MYSQL?
here for example 3 words are similar and thus the similarity should be something like:
count(similar words between @a and @b) / (count(@a)+count(@b) - count(intersection))
and thus the result is 3/(4 + 4 - 3)= 0.6
any idea is highly appreciated!
you can use this function (cop^H^H^Hadapted from http://www.artfulsoftware.com/infotree/queries.php#552):
CREATE FUNCTION `levenshtein`( s1 text, s2 text) RETURNS int(11)
DETERMINISTIC
BEGIN
DECLARE s1_len, s2_len, i, j, c, c_temp, cost INT;
DECLARE s1_char CHAR;
DECLARE cv0, cv1 text;
SET s1_len = CHAR_LENGTH(s1), s2_len = CHAR_LENGTH(s2), cv1 = 0x00, j = 1, i = 1, c = 0;
IF s1 = s2 THEN
RETURN 0;
ELSEIF s1_len = 0 THEN
RETURN s2_len;
ELSEIF s2_len = 0 THEN
RETURN s1_len;
ELSE
WHILE j <= s2_len DO
SET cv1 = CONCAT(cv1, UNHEX(HEX(j))), j = j + 1;
END WHILE;
WHILE i <= s1_len DO
SET s1_char = SUBSTRING(s1, i, 1), c = i, cv0 = UNHEX(HEX(i)), j = 1;
WHILE j <= s2_len DO
SET c = c + 1;
IF s1_char = SUBSTRING(s2, j, 1) THEN
SET cost = 0; ELSE SET cost = 1;
END IF;
SET c_temp = CONV(HEX(SUBSTRING(cv1, j, 1)), 16, 10) + cost;
IF c > c_temp THEN SET c = c_temp; END IF;
SET c_temp = CONV(HEX(SUBSTRING(cv1, j+1, 1)), 16, 10) + 1;
IF c > c_temp THEN
SET c = c_temp;
END IF;
SET cv0 = CONCAT(cv0, UNHEX(HEX(c))), j = j + 1;
END WHILE;
SET cv1 = cv0, i = i + 1;
END WHILE;
END IF;
RETURN c;
END
and for getting it as XX% use this function
CREATE FUNCTION `levenshtein_ratio`( s1 text, s2 text ) RETURNS int(11)
DETERMINISTIC
BEGIN
DECLARE s1_len, s2_len, max_len INT;
SET s1_len = LENGTH(s1), s2_len = LENGTH(s2);
IF s1_len > s2_len THEN
SET max_len = s1_len;
ELSE
SET max_len = s2_len;
END IF;
RETURN ROUND((1 - LEVENSHTEIN(s1, s2) / max_len) * 100);
END
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