比较两个字符串与PHP之间的相似性

时间:2016-07-01 02:25:59

标签: php similarity

嘿伙计:)我想要一些解决方案。现在,我有字典 words.txt ,这里有一些例子:

happy
laugh
sad

我有俚语

hppy

我想搜索&匹配俚语字符串到我的字典,这意味着它将返回" happy"因为这些字符串字典中引用" happy"

最近我一直在使用 similar_text(),但对其有效性并不充满信心。你能为我的问题推荐更好的解决方案吗?谢谢:))

在这里我把我的代码:

function searchwords($tweet){
//echo $tweet;
$find       = false;
$handle     = @fopen("words.txt", "r");
if ($handle)
{
    while (!feof($handle))
    {
        $buffer         = fgets($handle);
        similar_text(trim($tweet),trim($buffer),$percent);
        if ($percent == 100){ // this exact match
            $find = true;
        }else if ($percent >= 90){ //there is the possibility of errors
            $find = true;
        }

    }
    fclose($handle);
}
  if ($find == true){
    unset($tweet);
  }else{
    return $tweet;
  }
}

2 个答案:

答案 0 :(得分:6)

回答here

  

我发现要计算字符串之间的相似百分比,   LevenshteinJaro Winkler算法效果很好   拼写错误和字符串之间的小变化,而Smith Waterman Gotoh算法适用于重要的字符串   文本块将是相同的,但有"噪音"周围的   边缘。 This answer to a similar question显示了更多详细信息   此

我包含了使用这三个示例中的每一个的php示例来返回两个字符串之间的相似性百分比:

Levenshtein

echo levenshtein("LEGENDARY","BARNEY STINSON");

Jaro Winkler

class StringCompareJaroWinkler 
{
    public function compare($str1, $str2)
    {
        return $this->JaroWinkler($str1, $str2, $PREFIXSCALE = 0.1 );
    }

    private function getCommonCharacters( $string1, $string2, $allowedDistance ){

      $str1_len = mb_strlen($string1);
      $str2_len = mb_strlen($string2);
      $temp_string2 = $string2;

      $commonCharacters='';
      for( $i=0; $i < $str1_len; $i++){

        $noMatch = True;
        // compare if char does match inside given allowedDistance
        // and if it does add it to commonCharacters
        for( $j= max( 0, $i-$allowedDistance ); $noMatch && $j < min( $i + $allowedDistance + 1, $str2_len ); $j++){
          if( $temp_string2[$j] == $string1[$i] ){
            $noMatch = False;
        $commonCharacters .= $string1[$i];
        $temp_string2[$j] = '';
          }
        }
      }
      return $commonCharacters;
    }

    private function Jaro( $string1, $string2 ){

      $str1_len = mb_strlen( $string1 );
      $str2_len = mb_strlen( $string2 );

      // theoretical distance
      $distance = (int) floor(min( $str1_len, $str2_len ) / 2.0); 

      // get common characters
      $commons1 = $this->getCommonCharacters( $string1, $string2, $distance );
      $commons2 = $this->getCommonCharacters( $string2, $string1, $distance );

      if( ($commons1_len = mb_strlen( $commons1 )) == 0) return 0;
      if( ($commons2_len = mb_strlen( $commons2 )) == 0) return 0;
      // calculate transpositions
      $transpositions = 0;
      $upperBound = min( $commons1_len, $commons2_len );
      for( $i = 0; $i < $upperBound; $i++){
        if( $commons1[$i] != $commons2[$i] ) $transpositions++;
      }
      $transpositions /= 2.0;
      // return the Jaro distance
      return ($commons1_len/($str1_len) + $commons2_len/($str2_len) + ($commons1_len - $transpositions)/($commons1_len)) / 3.0;

    }

    private function getPrefixLength( $string1, $string2, $MINPREFIXLENGTH = 4 ){

      $n = min( array( $MINPREFIXLENGTH, mb_strlen($string1), mb_strlen($string2) ) );

      for($i = 0; $i < $n; $i++){
        if( $string1[$i] != $string2[$i] ){
          // return index of first occurrence of different characters 
          return $i;
        }
      }
      // first n characters are the same   
      return $n;
    }

    private function JaroWinkler($string1, $string2, $PREFIXSCALE = 0.1 ){

      $JaroDistance = $this->Jaro( $string1, $string2 );
      $prefixLength = $this->getPrefixLength( $string1, $string2 );
      return $JaroDistance + $prefixLength * $PREFIXSCALE * (1.0 - $JaroDistance);
    }
}

$jw = new StringCompareJaroWinkler();
echo $jw->compare("LEGENDARY","BARNEY STINSON");

Smith Waterman Gotoh

class SmithWatermanGotoh 
{
    private $gapValue;
    private $substitution;

    /**
     * Constructs a new Smith Waterman metric.
     * 
     * @param gapValue
     *            a non-positive gap penalty
     * @param substitution
     *            a substitution function
     */
    public function __construct($gapValue=-0.5, 
                $substitution=null) 
    {
        if($gapValue > 0.0) throw new Exception("gapValue must be <= 0");
        //if(empty($substitution)) throw new Exception("substitution is required");
        if (empty($substitution)) $this->substitution = new SmithWatermanMatchMismatch(1.0, -2.0);
        else $this->substitution = $substitution;
        $this->gapValue = $gapValue;
    }

    public function compare($a, $b) 
    {
        if (empty($a) && empty($b)) {
            return 1.0;
        }

        if (empty($a) || empty($b)) {
            return 0.0;
        }

        $maxDistance = min(mb_strlen($a), mb_strlen($b))
                * max($this->substitution->max(), $this->gapValue);
        return $this->smithWatermanGotoh($a, $b) / $maxDistance;
    }

    private function smithWatermanGotoh($s, $t) 
    {   
        $v0 = [];
        $v1 = [];
        $t_len = mb_strlen($t);
        $max = $v0[0] = max(0, $this->gapValue, $this->substitution->compare($s, 0, $t, 0));

        for ($j = 1; $j < $t_len; $j++) {
            $v0[$j] = max(0, $v0[$j - 1] + $this->gapValue,
                    $this->substitution->compare($s, 0, $t, $j));

            $max = max($max, $v0[$j]);
        }

        // Find max
        for ($i = 1; $i < mb_strlen($s); $i++) {
            $v1[0] = max(0, $v0[0] + $this->gapValue, $this->substitution->compare($s, $i, $t, 0));

            $max = max($max, $v1[0]);

            for ($j = 1; $j < $t_len; $j++) {
                $v1[$j] = max(0, $v0[$j] + $this->gapValue, $v1[$j - 1] + $this->gapValue,
                        $v0[$j - 1] + $this->substitution->compare($s, $i, $t, $j));

                $max = max($max, $v1[$j]);
            }

            for ($j = 0; $j < $t_len; $j++) {
                $v0[$j] = $v1[$j];
            }
        }

        return $max;
    }
}

class SmithWatermanMatchMismatch
{
    private $matchValue;
    private $mismatchValue;

    /**
     * Constructs a new match-mismatch substitution function. When two
     * characters are equal a score of <code>matchValue</code> is assigned. In
     * case of a mismatch a score of <code>mismatchValue</code>. The
     * <code>matchValue</code> must be strictly greater then
     * <code>mismatchValue</code>
     * 
     * @param matchValue
     *            value when characters are equal
     * @param mismatchValue
     *            value when characters are not equal
     */
    public function __construct($matchValue, $mismatchValue) {
        if($matchValue <= $mismatchValue) throw new Exception("matchValue must be > matchValue");

        $this->matchValue = $matchValue;
        $this->mismatchValue = $mismatchValue;
    }

    public function compare($a, $aIndex, $b, $bIndex) {
        return ($a[$aIndex] === $b[$bIndex] ? $this->matchValue
                : $this->mismatchValue);
    }

    public function max() {
        return $this->matchValue;
    }

    public function min() {
        return $this->mismatchValue;
    }
}

$o = new SmithWatermanGotoh();
echo $o->compare("LEGENDARY","BARNEY STINSON");

答案 1 :(得分:0)

希望它能满足你的目的。但是在使用similar_text()时需要注意一些事项。

  1. 匹配百分比可能因参数的顺序而异。 ie:similar_text($a, $b, $percent)similar_text($b, $a, $percent)在这两种情况下,$ percent可能不相同。
  2. 请注意,此函数区分大小写:因此传递$ a和$ b时会传递大写或小写。
  3. 了解详情this page

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