note 51600 added to function.levenshtein

<?php /********************************************************************* * The below func, btlfsa, (better than levenstien for spelling apps) * produces better results when comparing words like haert against * haart and heart. * * For example here is the output of levenshtein compared to btlfsa * when comparing 'haert' to 'herat, haart, heart, harte' * * btlfsa('haert','herat'); output is.. 3 * btlfsa('haert','haart'); output is.. 3 * btlfsa('haert','harte'); output is.. 3 * btlfsa('haert','heart'); output is.. 2 * * levenshtein('haert','herat'); output is.. 2 * levenshtein('haert','haart'); output is.. 1 * levenshtein('haert','harte'); output is.. 2 * levenshtein('haert','heart'); output is.. 2 * * In other words, if you used levenshtein, 'haart' would be the * closest match to 'haert'. Where as, btlfsa sees that it should be * 'heart' */ function btlfsa($word1,$word2) { $score = 0; // For each char that is different add 2 to the score // as this is a BIG difference $remainder = preg_replace("/[".preg_replace("/[^A-Za-z0-9\']/",' ',$word1)."]/i",'',$word2); $remainder .= preg_replace("/[".preg_replace("/[^A-Za-z0-9\']/",' ',$word2)."]/i",'',$word1); $score = strlen($remainder)*2; // Take the difference in string length and add it to the score $w1_len = strlen($word1); $w2_len = strlen($word2); $score += $w1_len > $w2_len ? $w1_len - $w2_len : $w2_len - $w1_len; // Calculate how many letters are in different locations // And add it to the score i.e. // // h e a r t // 1 2 3 4 5 // // h a e r t a e = 2 // 1 2 3 4 5 1 2 3 4 5 // $w1 = $w1_len > $w2_len ? $word1 : $word2; $w2 = $w1_len > $w2_len ? $word2 : $word1; for($i=0; $i < strlen($w1); $i++) { if ( !isset($w2[$i]) || $w1[$i] != $w2[$i] ) { $score++; } } return $score; } // ************************************************************* // Here is a full code example showing the difference $misspelled = 'haert'; // Imagine that these are sample suggestions thrown back by soundex or metaphone.. $suggestions = array('herat', 'haart', 'heart', 'harte'); // Firstly order an array based on levenshtein $levenshtein_ordered = array(); foreach ( $suggestions as $suggestion ) { $levenshtein_ordered[$suggestion] = levenshtein($misspelled,$suggestion); } asort($levenshtein_ordered, SORT_NUMERIC ); print "<b>Suggestions as ordered by levenshtein...</b><ul><pre>"; print_r($levenshtein_ordered); print "</pre></ul>"; // Secondly order an array based on btlfsa $btlfsa_ordered = array(); foreach ( $suggestions as $suggestion ) { $btlfsa_ordered[$suggestion] = btlfsa($misspelled,$suggestion); } asort($btlfsa_ordered, SORT_NUMERIC ); print "<b>Suggestions as ordered by btlfsa...</b><ul><pre>"; print_r($btlfsa_ordered); print "</pre></ul>"; ?> ---- Manual Page -- http://www.php.net/manual/en/function.levenshtein.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+51600 Delete: added to the manual -- http://master.php.net/manage/user-notes.php?action=delete+51600&report=yes&reason=added+to+the+manual Delete: bad code -- http://master.php.net/manage/user-notes.php?action=delete+51600&report=yes&reason=bad+code Delete: spam -- http://master.php.net/manage/user-notes.php?action=delete+51600&report=yes&reason=spam Delete: useless -- http://master.php.net/manage/user-notes.php?action=delete+51600&report=yes&reason=useless Delete: other reasons -- http://master.php.net/manage/user-notes.php?action=delete+51600&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+51600&report=yes Search -- http://master.php.net/manage/user-notes.php