def range_count(x, min, max):
    """
    Count observed values within the interval [min, max).

    :param x: the time series to calculate the feature of
    :type x: pandas.Series
    :param min: the inclusive lower bound of the range
    :type min: int or float
    :param max: the exclusive upper bound of the range
    :type max: int or float
    :return: the count of values within the range
    :rtype: int
    """

    return x[(x >= min) & (x < max)].count()