Cosine similarity vs Hamming distance [closed]

Answer 1

I apologize for ignoring the fact that you said that you didn't want to use any other algorithms, but seriously, Levenshtein distance and Damerau-Levenshtein distance are way more freakin' useful than Hamming distance. Here's a D-L distance implementation in PHP, and if you don't like PHP's native levenshtein() function, which I think you won't because it has a length limit, here's a non-length-limited version:

function levenshtein_distance($text1, $text2) {
    $len1 = strlen($text1);
    $len2 = strlen($text2);
    for($i = 0; $i <= $len1; $i++)
        $distance[$i][0] = $i;
    for($j = 0; $j <= $len2; $j++)
        $distance[0][$j] = $j;
    for($i = 1; $i <= $len1; $i++)
        for($j = 1; $j <= $len2; $j++)
            $distance[$i][$j] = min($distance[$i - 1][$j] + 1, $distance[$i][$j - 1] + 1, $distance[$i - 1][$j - 1] + ($text1[$i - 1] != $text2[$j - 1]));
    return $distance[$len1][$len2];
}