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| 1 | +import tensorflow as tf |
| 2 | +import copy |
| 3 | + |
| 4 | + |
| 5 | +class PPOTrain: |
| 6 | + def __init__(self, Policy, Old_Policy, gamma=0.95, clip_value=0.2, c_1=1, c_2=0.01, logger=None, args=None): |
| 7 | + """ |
| 8 | + :param Policy: |
| 9 | + :param Old_Policy: |
| 10 | + :param gamma: |
| 11 | + :param clip_value: |
| 12 | + :param c_1: parameter for value difference |
| 13 | + :param c_2: parameter for entropy bonus |
| 14 | + :param logger: hyper-parameter Saver |
| 15 | + :param is_log: wheter save the hyper-parameter |
| 16 | + """ |
| 17 | + |
| 18 | + self.Policy = Policy |
| 19 | + self.Old_Policy = Old_Policy |
| 20 | + self.gamma = gamma |
| 21 | + self.logger = logger |
| 22 | + self.args = args |
| 23 | + |
| 24 | + pi_trainable = self.Policy.get_trainable_variables() |
| 25 | + old_pi_trainable = self.Old_Policy.get_trainable_variables() |
| 26 | + |
| 27 | + # assign_operations for policy parameter values to old policy parameters |
| 28 | + with tf.variable_scope('assign_op'): |
| 29 | + self.assign_ops = [] |
| 30 | + for v_old, v in zip(old_pi_trainable, pi_trainable): |
| 31 | + self.assign_ops.append(tf.assign(v_old, v)) |
| 32 | + |
| 33 | + # inputs for train_op |
| 34 | + with tf.variable_scope('train_inp'): |
| 35 | + self.actions = tf.placeholder(dtype=tf.int32, shape=[None], name='actions') |
| 36 | + self.rewards = tf.placeholder(dtype=tf.float32, shape=[None], name='rewards') |
| 37 | + self.v_preds_next = tf.placeholder(dtype=tf.float32, shape=[None], name='v_preds_next') |
| 38 | + self.gaes = tf.placeholder(dtype=tf.float32, shape=[None], name='gaes') |
| 39 | + |
| 40 | + act_probs = self.Policy.act_probs |
| 41 | + act_probs_old = self.Old_Policy.act_probs |
| 42 | + |
| 43 | + # agent通过新策略选择action的概率 probabilities of actions which agent took with policy |
| 44 | + act_probs = act_probs * tf.one_hot(indices=self.actions, depth=act_probs.shape[1]) |
| 45 | + act_probs = tf.reduce_sum(act_probs, axis=1) |
| 46 | + |
| 47 | + # agent通过旧策略选择action的概率 probabilities of actions which agent took with old policy |
| 48 | + act_probs_old = act_probs_old * tf.one_hot(indices=self.actions, depth=act_probs_old.shape[1]) |
| 49 | + act_probs_old = tf.reduce_sum(act_probs_old, axis=1) |
| 50 | + |
| 51 | + with tf.variable_scope('PPO_loss'): |
| 52 | + """ |
| 53 | + 策略目标函数 |
| 54 | + """ |
| 55 | + # |
| 56 | + # ratios = tf.divide(act_probs, act_probs_old) |
| 57 | + # r_t(θ) = π/πold 为了防止除数为0,这里截取一下值,然后使用e(log减法)来代替直接除法 |
| 58 | + ratios = tf.exp(tf.log(tf.clip_by_value(act_probs, 1e-10, 1.0)) - tf.log(tf.clip_by_value(act_probs_old, 1e-10, 1.0))) |
| 59 | + # L_CLIP 裁剪优势函数值 |
| 60 | + clipped_ratios = tf.clip_by_value(ratios, clip_value_min=1 - clip_value, clip_value_max=1 + clip_value) |
| 61 | + self.loss_clip = tf.minimum(tf.multiply(self.gaes, ratios), tf.multiply(self.gaes, clipped_ratios)) |
| 62 | + self.loss_clip = tf.reduce_mean(self.loss_clip) |
| 63 | + |
| 64 | + """ |
| 65 | + 策略模型的熵 |
| 66 | + """ |
| 67 | + # 计算新策略πθ的熵 S = -p log(p) 这里裁剪防止p=0 |
| 68 | + self.entropy = -tf.reduce_sum(self.Policy.act_probs * tf.log(tf.clip_by_value(self.Policy.act_probs, 1e-10, 1.0)), axis=1) |
| 69 | + self.entropy = tf.reduce_mean(self.entropy, axis=0) # mean of entropy of pi(obs) |
| 70 | + |
| 71 | + """ |
| 72 | + 值目标函数 |
| 73 | + """ |
| 74 | + # L_vf = [(r+γV(π(st+1))) - (V(π(st)))]^2 |
| 75 | + v_preds = self.Policy.v_preds |
| 76 | + self.loss_vf = tf.squared_difference(self.rewards + self.gamma * self.v_preds_next, v_preds) |
| 77 | + self.loss_vf = tf.reduce_mean(self.loss_vf) |
| 78 | + |
| 79 | + # construct computation graph for loss |
| 80 | + # L(θ) = E_hat[L_CLIP(θ) - c1 L_VF(θ) + c2 S[πθ](s)] |
| 81 | + # L = 策略目标函数 + 值目标函数 + 策略模型的熵 |
| 82 | + self.loss = self.loss_clip - c_1 * self.loss_vf + c_2 * self.entropy |
| 83 | + # minimize -loss == maximize loss |
| 84 | + self.loss = -self.loss |
| 85 | + |
| 86 | + optimizer = tf.train.RMSPropOptimizer(learning_rate=args.ppo_lr, epsilon=1e-5) |
| 87 | + self.gradients = optimizer.compute_gradients(self.loss, var_list=pi_trainable) |
| 88 | + self.train_op = optimizer.minimize(self.loss, var_list=pi_trainable) |
| 89 | + |
| 90 | + |
| 91 | + def train(self, obs, actions, gaes, rewards, v_preds_next): |
| 92 | + tf.get_default_session().run(self.train_op, feed_dict={self.Policy.obs: obs, |
| 93 | + self.Old_Policy.obs: obs, |
| 94 | + self.actions: actions, |
| 95 | + self.rewards: rewards, |
| 96 | + self.v_preds_next: v_preds_next, |
| 97 | + self.gaes: gaes}) |
| 98 | + |
| 99 | + def log_parameter(self, obs, actions, gaes, rewards, v_preds_next): |
| 100 | + lc, ent, lvf, loss = tf.get_default_session().run([self.loss_clip, self.entropy, self.loss_vf, self.loss], feed_dict={self.Policy.obs: obs, |
| 101 | + self.Old_Policy.obs: obs, |
| 102 | + self.actions: actions, |
| 103 | + self.rewards: rewards, |
| 104 | + self.v_preds_next: v_preds_next, |
| 105 | + self.gaes: gaes}) |
| 106 | + |
| 107 | + log_dict = { |
| 108 | + 'ppo_loss_clip': lc, |
| 109 | + 'ppo_entropy': ent, |
| 110 | + 'ppo_value_difference': lvf, |
| 111 | + 'ppo_total = (Lclip+Lvf+S)': loss |
| 112 | + } |
| 113 | + |
| 114 | + self.logger.log_parameter(log_dict) |
| 115 | + |
| 116 | + def assign_policy_parameters(self): |
| 117 | + # assign policy parameter values to old policy parameters |
| 118 | + return tf.get_default_session().run(self.assign_ops) |
| 119 | + |
| 120 | + def get_gaes(self, rewards, v_preds, v_preds_next): |
| 121 | + """ |
| 122 | + GAE |
| 123 | + :param rewards: r(t) |
| 124 | + :param v_preds: v(st) |
| 125 | + :param v_preds_next: v(st+1) |
| 126 | + :return: |
| 127 | + """ |
| 128 | + deltas = [r_t + self.gamma * v_next - v for r_t, v_next, v in zip(rewards, v_preds_next, v_preds)] |
| 129 | + |
| 130 | + # calculate generative advantage estimator(lambda = 1), see ppo paper eq(11) |
| 131 | + gaes = copy.deepcopy(deltas) |
| 132 | + for t in reversed(range(len(gaes) - 1)): # is T-1, where T is time step which run policy |
| 133 | + gaes[t] = gaes[t] + self.gamma * gaes[t + 1] |
| 134 | + return gaes |
| 135 | + |
| 136 | + def get_grad(self, obs, actions, gaes, rewards, v_preds_next): |
| 137 | + return tf.get_default_session().run(self.gradients, feed_dict={self.Policy.obs: obs, |
| 138 | + self.Old_Policy.obs: obs, |
| 139 | + self.actions: actions, |
| 140 | + self.rewards: rewards, |
| 141 | + self.v_preds_next: v_preds_next, |
| 142 | + self.gaes: gaes}) |
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