def __init__(self, groups=None):
        super(GroupedRequirements, self).__init__(NamedRequirements)
        self.groups = groups or self.default_groups
        self.filename = None
        self.create_default_groups()
def __update_mean(self, rc, mc):
        mean = 0.0
        for index_point in range(len(self.__data)):
            mean += rc[index_point] * self.__data[index_point]