Caleb Pitman Caleb Pitman - 2 months ago 11
PHP Question

how to preg match a string with a levenshtein distance in PHP

How can I preg match a string, but tolerate a variable levensthein distance in the pattern?

$string = 'i eat apples and oranges all day long';
$find = 'and orangis';
$distance = 1;
$matches = pregMatch_withLevensthein($find, $distance, $string);


This would return 'and oranges';

Answer

By converting the search string into a regexp, we can match the pattern. Then we search using that regexp and do a comparison with levenshtein. If it matches the bounds we can return the values.

$string = 'i eat apples and oranges all day long';
$find = 'and orangis';
$distance = 1;
$matches = preg_match_levensthein($find, $distance, $string);
var_dump($matches);

function preg_match_levensthein($find, $distance, $string)
{
    $found = array();

    // Covert find into regex
    $parts = explode(' ', $find);
    $regexes = array();
    foreach ($parts as $part) {
        $regexes[] = '[a-z0-9]{' . strlen($part) . '}';
    }
    $regexp = '#' . implode('\s', $regexes) . '#i';

    // Find all matches
    preg_match_all($regexp, $string, $matches);

    foreach ($matches as $match) {
        // Check levenshtein distance and add to the found if within bounds
        if (levenshtein($match[0], $find) <= $distance) {
            $found[] = $match[0];
        }
    }

    // return found
    return $found;
}
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