A3C 源碼解析
標籤（空格分隔）： 增強學習算法 源碼
該代碼實現連續空間的策略控制
"""
Asynchronous Advantage Actor Critic (A3C) with continuous action space, Reinforcement Learning.
Using:
tensorflow r1.3
gym 0.8.0
"""
import multiprocessing
import threading
import tensorflow as tf
import numpy as np
import gym
import os
import shutil
import matplotlib.pyplot as plt
GAME = 'Pendulum-v0'
OUTPUT_GRAPH = True
LOG_DIR = './log'
N_WORKERS = multiprocessing.cpu_count()
MAX_EP_STEP = 200
MAX_GLOBAL_EP = 2000
GLOBAL_NET_SCOPE = 'Global_Net' #全局網絡
UPDATE_GLOBAL_ITER = 10
GAMMA = 0.9
ENTROPY_BETA = 0.01
LR_A = 0.0001 # learning rate for actor
LR_C = 0.001 # learning rate for critic
GLOBAL_RUNNING_R = []
GLOBAL_EP = 0
env = gym.make(GAME)
N_S = env.observation_space.shape[0]
N_A = env.action_space.shape[0]
A_BOUND = [env.action_space.low, env.action_space.high] #連續動作的下上限
class ACNet(object):
def __init__(self, scope, globalAC=None):
if scope == GLOBAL_NET_SCOPE: # get global network
with tf.variable_scope(scope):
self.s = tf.placeholder(tf.float32, [None, N_S], 'S')
self.a_params, self.c_params = self._build_net(scope)[-2:] #創建Actor-Critic網絡圖
else: # local net, calculate losses
with tf.variable_scope(scope):
self.s = tf.placeholder(tf.float32, [None, N_S], 'S')
self.a_his = tf.placeholder(tf.float32, [None, N_A], 'A') #當前狀態動作輸入
self.v_target = tf.placeholder(tf.float32, [None, 1], 'Vtarget') #target value的輸入
mu, sigma, self.v, self.a_params, self.c_params = self._build_net(scope) #返回mu,sigma 以及 兩個網絡的學習參數
td = tf.subtract(self.v_target, self.v, name='TD_error') #value做差，TD-error
with tf.name_scope('c_loss'):
self.c_loss = tf.reduce_mean(tf.square(td)) #critic 網絡的損失函數
with tf.name_scope('wrap_a_out'):
mu, sigma = mu * A_BOUND[1], sigma + 1e-4 #在連續空間相當於action 注意的是這裏是採樣！！！！！！
normal_dist = tf.distributions.Normal(mu, sigma)
with tf.name_scope('a_loss'):
log_prob = normal_dist.log_prob(self.a_his) #actor的損失函數
exp_v = log_prob * td
entropy = normal_dist.entropy() # encourage exploration
self.exp_v = ENTROPY_BETA * entropy + exp_v
self.a_loss = tf.reduce_mean(-self.exp_v)
with tf.name_scope('choose_a'): # use local params to choose action
self.A = tf.clip_by_value(tf.squeeze(normal_dist.sample(1), axis=0), A_BOUND[0], A_BOUND[1])
with tf.name_scope('local_grad'): #分別對 actor 和critic 的參數求導 梯度
self.a_grads = tf.gradients(self.a_loss, self.a_params)
self.c_grads = tf.gradients(self.c_loss, self.c_params)
with tf.name_scope('sync'):
with tf.name_scope('pull'): #將全局網絡的參數 送往局部網絡
self.pull_a_params_op = [l_p.assign(g_p) for l_p, g_p in zip(self.a_params, globalAC.a_params)]
self.pull_c_params_op = [l_p.assign(g_p) for l_p, g_p in zip(self.c_params, globalAC.c_params)]
with tf.name_scope('push'): #對全局網絡的參數求導 並優化
self.update_a_op = OPT_A.apply_gradients(zip(self.a_grads, globalAC.a_params))
self.update_c_op = OPT_C.apply_gradients(zip(self.c_grads, globalAC.c_params))
def _build_net(self, scope):
w_init = tf.random_normal_initializer(0., .1)
with tf.variable_scope('actor'):
l_a = tf.layers.dense(self.s, 200, tf.nn.relu6, kernel_initializer=w_init, name='la')
mu = tf.layers.dense(l_a, N_A, tf.nn.tanh, kernel_initializer=w_init, name='mu')
sigma = tf.layers.dense(l_a, N_A, tf.nn.softplus, kernel_initializer=w_init, name='sigma')
with tf.variable_scope('critic'):
l_c = tf.layers.dense(self.s, 100, tf.nn.relu6, kernel_initializer=w_init, name='lc')
v = tf.layers.dense(l_c, 1, kernel_initializer=w_init, name='v') # state value
a_params = tf.get_collection(tf.GraphKeys.TRAINABLE_VARIABLES, scope=scope + '/actor')
c_params = tf.get_collection(tf.GraphKeys.TRAINABLE_VARIABLES, scope=scope + '/critic')
return mu, sigma, v, a_params, c_params
def update_global(self, feed_dict): # run by a local 訓練全局網絡
SESS.run([self.update_a_op, self.update_c_op], feed_dict) # local grads applies to global net
def pull_global(self): # run by a local 更新局部網絡
SESS.run([self.pull_a_params_op, self.pull_c_params_op])
def choose_action(self, s): # run by a local
s = s[np.newaxis, :]
return SESS.run(self.A, {self.s: s})[0]
class Worker(object): #工作類 該類主要協同多線程對 全局網絡進行學習 並更新局部網絡
def __init__(self, name, globalAC):
self.env = gym.make(GAME).unwrapped
self.name = name
self.AC = ACNet(name, globalAC) # 將全局網絡 和 局部網絡聯繫起來
def work(self):
global GLOBAL_RUNNING_R, GLOBAL_EP
total_step = 1
buffer_s, buffer_a, buffer_r = [], [], [] #存儲最近幾次的狀態，動作，
while not COORD.should_stop() and GLOBAL_EP < MAX_GLOBAL_EP:
s = self.env.reset()
ep_r = 0
for ep_t in range(MAX_EP_STEP):
if self.name == 'W_0':
self.env.render()
a = self.AC.choose_action(s)
s_, r, done, info = self.env.step(a)
done = True if ep_t == MAX_EP_STEP - 1 else False
ep_r += r
buffer_s.append(s)
buffer_a.append(a)
buffer_r.append((r+8)/8) # normalize
if total_step % UPDATE_GLOBAL_ITER == 0 or done: # update global and assign to local net
if done:
v_s_ = 0 # terminal
else:
v_s_ = SESS.run(self.AC.v, {self.AC.s: s_[np.newaxis, :]})[0, 0]
buffer_v_target = []
for r in buffer_r[::-1]: # reverse buffer r
v_s_ = r + GAMMA * v_s_
buffer_v_target.append(v_s_)
buffer_v_target.reverse()
buffer_s, buffer_a, buffer_v_target = np.vstack(buffer_s), np.vstack(buffer_a), np.vstack(buffer_v_target)
feed_dict = {
self.AC.s: buffer_s,
self.AC.a_his: buffer_a,
self.AC.v_target: buffer_v_target,
}
self.AC.update_global(feed_dict)
buffer_s, buffer_a, buffer_r = [], [], []
self.AC.pull_global()
s = s_
total_step += 1
if done:
if len(GLOBAL_RUNNING_R) == 0: # record running episode reward
GLOBAL_RUNNING_R.append(ep_r)
else:
GLOBAL_RUNNING_R.append(0.9 * GLOBAL_RUNNING_R[-1] + 0.1 * ep_r)
print(
self.name,
"Ep:", GLOBAL_EP,
"| Ep_r: %i" % GLOBAL_RUNNING_R[-1],
)
GLOBAL_EP += 1
break
if __name__ == "__main__":
SESS = tf.Session()
with tf.device("/cpu:0"):
OPT_A = tf.train.RMSPropOptimizer(LR_A, name='RMSPropA')
OPT_C = tf.train.RMSPropOptimizer(LR_C, name='RMSPropC')
GLOBAL_AC = ACNet(GLOBAL_NET_SCOPE) # we only need its params
workers = []
# Create worker
for i in range(N_WORKERS):
i_name = 'W_%i' % i # worker name
workers.append(Worker(i_name, GLOBAL_AC))
COORD = tf.train.Coordinator()
SESS.run(tf.global_variables_initializer())
if OUTPUT_GRAPH:
if os.path.exists(LOG_DIR):
shutil.rmtree(LOG_DIR)
tf.summary.FileWriter(LOG_DIR, SESS.graph)
worker_threads = []
for worker in workers:
job = lambda: worker.work()
t = threading.Thread(target=job)
t.start()
worker_threads.append(t)
COORD.join(worker_threads)
plt.plot(np.arange(len(GLOBAL_RUNNING_R)), GLOBAL_RUNNING_R)
plt.xlabel('step')
plt.ylabel('Total moving reward')
plt.show()
