Adding categories via php script

My goal is to add categories if there is a one of specified keywords in title description or both.
I am trying to execute a php script using feeds php tamper module my problem is that I don't know how I should I format term ids...

$title = $item['jsonpath_parser:1'];
$description = $item['jsonpath_parser:2'];

$keywords = array(
	'1' => array('tags1', 'tag2'),
	'2' => array('tg3','tags','lorem'),
	'3' => array('ipsum', 'dor'),
	'4' => array('set', 'amet'),
	'5' => array('et'),
	'6' => array('ista', 'kulpa', 'la'),
	'7' => array('bora') );

$cat_list = array();

foreach ($keywords as $cat => $tags) {
	foreach ($tags as $key => $tag) {
		if (strpos($title, $tag) !== false && strpos($description, $tag) !== false) {
			array_push($cat_list, $cat);
		}
	}
}

return implode(',', $cat_list);