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<?php //http://stackoverflow.com/questions/653157/a-better-similarity-ranking-algorithm-for-variable-length-strings class StringMatch{ public static function compare($a, $b){ $pairsA = self::wordLetterPairs($a); $pairsB = self::wordLetterPairs($b); $union = count($pairsA) + count($pairsB); $intersect = count(array_intersect($pairsA, $pairsB)); return 2*$intersect/$union; } public static function letterPairs($str){ $pairCount = strlen($str)-1; //don't compute every time in if $pairs = array(); for($i = 0; $i < $pairCount; $i++){ $pairs[] = substr($str, $i, 2); } return $pairs; } public static function wordLetterPairs($str){ $allPairs = array(); $str = explode(" ", $str); //get pairs in each word foreach($str as $w){ $pairs = self::letterPairs($w); //make sure, no doubled pairs are included foreach($pairs as $p){ $allPairs[$p] = $p; } } return array_values($allPairs); } } var_dump(StringMatch::compare("GutenTag Frau Fickerin", "Ficker Herr GutenTag"));