LevenshteinDistance extension for php-nlp-tools

LevenshteinDistance.php

<?php
namespace App\Utilities;


/**
 * This class implements the LevenshteinDistance distance of two strings or sets.
 * This accepts strings of arbitrary lengths.
 * 
 */

class LevenshteinDistance
{
    /**
     * Count the number of positions that A and B differ.
     *
     * @param  string|array $A
     * @param  string|array $B
     * @return int    The Levenshtein distance of the two strings A and B
     */
    public function dist($A, $B)
    {

         if(is_array($A)) {
             $m = count($A);
         }
         elseif(is_string($A)) {
             $m = strlen($A);
         }
         else {
            throw new \InvalidArgumentException(
                 "LevenshteinDistance accepts only strings or arrays"
            );
         }

         if (is_array($B)){
             $n = count($B);
         }
         else if (is_string($B)){
             $n = strlen($B);
         }
         else {
             throw new \InvalidArgumentException(
                 "LevenshteinDistance accepts only strings or arrays"
                 );
         }
            
        
        for($i=0;$i<=$m;$i++) $d[$i][0] = $i;
        for($j=0;$j<=$n;$j++) $d[0][$j] = $j;
        
        for($i=1;$i<=$m;$i++) {
            for($j=1;$j<=$n;$j++) {
                $c = ($A[$i-1] == $B[$j-1])?0:1;
                $d[$i][$j] = min($d[$i-1][$j]+1,$d[$i][$j-1]+1,$d[$i-1][$j-1]+$c);
            }
        }

        return $d[$m][$n];
    }
}