/**
* Static method extractTags
*
* @param string $content # input content
* @param int $top_k # top_k
* @param array $options # other options
*
* @return array $tags
*/
public static function extractTags($content, $top_k = 20, $options = array())
{
$defaults = array('mode' => 'default');
$options = array_merge($defaults, $options);
$tags = array();
$words = Jieba::cut($content);
$freq = array();
$total = 0.0;
foreach ($words as $w) {
$w = trim($w);
if (mb_strlen($w, 'UTF-8') < 2) {
continue;
}
if (isset($freq[$w])) {
$freq[$w] = $freq[$w] + 1.0;
} else {
$freq[$w] = 0.0 + 1.0;
}
$total = $total + 1.0;
}
foreach ($freq as $k => $v) {
$freq[$k] = $v / $total;
}
$tf_idf_list = array();
foreach ($freq as $k => $v) {
if (isset(self::$idf_freq[$k])) {
$idf_freq = self::$idf_freq[$k];
} else {
$idf_freq = self::$max_idf;
}
$tf_idf_list[$k] = $v * $idf_freq;
}
arsort($tf_idf_list);
$tags = array_slice($tf_idf_list, 0, $top_k, true);
return $tags;
}