def __create_navigator(self, main_root):
		navigator_dir = os.path.join(main_root, 'navigator')
		safe_mkdir(navigator_dir)

		navigators = self.__config_mgr.navigator()
		self.__navigator_mgr.create_navigators(navigators, navigator_dir)
def _cost_gp(self,x):
        """
        Predicts the time cost of evaluating the function at x.
        """
        m, _, _, _ = self.cost_model.predict_withGradients(x)
        return np.exp(m)