crodas\TextRank\POS\English\Tagger::tag PHP Method

    public static function tag(array $words)
    {
        static $dict;
        if (empty($dict)) {
            $dict = (require __DIR__ . '/lexicon.php');
        }
        $tmp = [];
        $return = [];
        $nouns = ['NN', 'NNS'];
        $i = 0;
        foreach ($words as $id => $token) {
            $tmp[$i] = ['token' => $token, 'tag' => 'NN'];
            $return[$id] =& $tmp[$i];
            // remove trailing full stops
            if (substr($token, -1) == '.') {
                $token = preg_replace('/\\.+$/', '', $token);
            }
            // get from dict if set
            if (!empty($dict[$token])) {
                $tmp[$i]['tag'] = $dict[$token][0];
            }
            // Converts verbs after 'the' to nouns
            if ($i > 0) {
                if ($tmp[$i - 1]['tag'] == 'DT' && in_array($tmp[$i]['tag'], array('VBD', 'VBP', 'VB'))) {
                    $tmp[$i]['tag'] = 'NN';
                }
            }
            // Convert noun to number if . appears
            if ($tmp[$i]['tag'][0] == 'N' && strpos($token, '.') !== false) {
                $tmp[$i]['tag'] = 'CD';
            }
            // Convert noun to past particile if ends with 'ed'
            if ($tmp[$i]['tag'][0] == 'N' && substr($token, -2) == 'ed') {
                $tmp[$i]['tag'] = 'VBN';
            }
            // Anything that ends 'ly' is an adverb
            if (substr($token, -2) == 'ly') {
                $tmp[$i]['tag'] = 'RB';
            }
            // Common noun to adjective if it ends with al
            if (in_array($tmp[$i]['tag'], $nouns) && substr($token, -2) == 'al') {
                $tmp[$i]['tag'] = 'JJ';
            }
            // Noun to verb if the word before is 'would'
            if ($i > 0) {
                if ($tmp[$i]['tag'] == 'NN' && $tmp[$i - 1]['token'] == 'would') {
                    $tmp[$i]['tag'] = 'VB';
                }
            }
            // Convert noun to plural if it ends with an s
            if ($tmp[$i]['tag'] == 'NN' && substr($token, -1) == 's') {
                $tmp[$i]['tag'] = 'NNS';
            }
            // Convert common noun to gerund
            if (in_array($tmp[$i]['tag'], $nouns) && substr($token, -3) == 'ing') {
                $tmp[$i]['tag'] = 'VBG';
            }
            // If we get noun noun, and the second can be a verb, convert to verb
            if ($i > 0) {
                if (in_array($tmp[$i]['tag'], $nouns) && in_array($tmp[$i - 1]['tag'], $nouns) && isset($dict[$token])) {
                    if (in_array('VBN', $dict[$token])) {
                        $tmp[$i]['tag'] = 'VBN';
                    } else {
                        if (in_array('VBZ', $dict[$token])) {
                            $tmp[$i]['tag'] = 'VBZ';
                        }
                    }
                }
            }
            $i++;
        }
        return $return;
    }