GradientBoostingAgentClass.py 文件源码

def add_new_weak_learner(self):
        '''
        Summary:
            Adds a new function, h, to self.weak_learners by solving for Eq. 1 using multiple additive regression trees:

            [Eq. 1] h = argmin_h (sum_i Q_A(s_i,a_i) + h(s_i, a_i) - (r_i + max_b Q_A(s'_i, b)))

        '''
        if len(self.most_recent_episode) == 0:
            # If this episode contains no data, don't do anything.
            return

        # Build up data sets of features and loss terms
        data = np.zeros((len(self.most_recent_episode), self.max_state_features + 1))
        total_loss = np.zeros(len(self.most_recent_episode))

        for i, experience in enumerate(self.most_recent_episode):
            # Grab the experience.
            s, a, r, s_prime = experience

            # Pad in case the state features are too short (as in Atari sometimes).
            features = self._pad_features_with_zeros(s, a)
            loss = (r + self.gamma * self.get_max_q_value(s_prime) - self.get_q_value(s, a))

            # Add to relevant lists.
            data[i] = features
            total_loss[i] = loss

        # Compute new regressor and add it to the weak learners.
        estimator = GradientBoostingRegressor(loss='ls', n_estimators=1, max_depth=self.max_depth)
        estimator.fit(data, total_loss)
        self.weak_learners.append(estimator)