library/Rediska/Key/SortedSet.php
public function getLengthByScore($min, $max)
    {
        return $this->_getRediskaOn()->getSortedSetLengthByScore($this->getName(), $min, $max);
    }
public function getLengthByScore($min, $max)
    {
        return $this->_getRediskaOn()->getSortedSetLengthByScore($this->getName(), $min, $max);
    }
Get count of members from sorted set by min and max score

@param integer $min Min score
@param integer $max Max score
@return integer