Returns the last location of the minimal value of x.
    The position is calculated relatively to the length of x.

    :param x: the time series to calculate the feature of
    :type x: numpy.ndarray
    :return: the value of this feature
    :return type: float

def last_location_of_minimum(x):
    """
    Returns the last location of the minimal value of x.
    The position is calculated relatively to the length of x.

    :param x: the time series to calculate the feature of
    :type x: numpy.ndarray
    :return: the value of this feature
    :return type: float
    """
    x = np.asarray(x)
    return 1.0 - np.argmin(x[::-1]) / len(x) if len(x) > 0 else np.NaN