Question

What is the fastest way in PHP to take a keyword list and match it to a search result (like an array of titles) for all words?

For instance, if my keyword phrase is “great leather shoes“, then the following titles would be a match…

• Get Some Really Great Leather Shoes
• Leather Shoes Are Great
• Great Day! Those Are Some Cool Leather Shoes!
• Shoes, Made of Leather, Can Be Great

…while these would not be a match:

• Leather Shoes on Sale Today!
• You’ll Love These Leather Shoes Greatly
• Great Shoes Don’t Come Cheap

I imagine there’s some trick with array functions or a RegEx (Regular Expression) to achieve this rapidly.

Answer 1

I would use an index for the words in the titles and test if every search term is in that index:

$terms = explode(' ', 'great leather shoes');
$titles = array(
    'Get Some Really Great Leather Shoes',
    'Leather Shoes Are Great',
    'Great Day! Those Are Some Cool Leather Shoes!',
    'Shoes, Made of Leather, Can Be Great'
);
foreach ($titles as $title) {
    // extract words in lowercase and use them as key for the word index
    $wordIndex = array_flip(preg_split('/\P{L}+/u', mb_strtolower($title), -1, PREG_SPLIT_NO_EMPTY));
    // look up if every search term is in the index
    foreach ($terms as $term) {
        if (!isset($wordIndex[$term])) {
            // if one is missing, continue with the outer foreach
            continue 2;
        }
    }
    // echo matched title
    echo "match: $title";
}