LMongo\Query\Builder::aggregate PHP Method

    public function aggregate($function, $column, $query = array())
    {
        if (0 == count($query)) {
            $query = $this->compileWheres($this);
        }
        $pipeline = array();
        if (count($query)) {
            $pipeline[] = array('$match' => $query);
        }
        $pipeline[] = array('$group' => array('_id' => 0, $function => array('$' . $function => '$' . $column)));
        $result = $this->connection->{$this->collection}->aggregate($pipeline);
        if (1 == (int) $result['ok'] and isset($result['result'][0][$function])) {
            return $result['result'][0][$function];
        }
        return 0;
    }