Add DDPG example (#36)

* add DDPG example, fix some tiny bug

* add license

* unify code structure

* unify code structure

* refine gputils, fix seed in QuickStart

* use white noise in DDPG

* fix codestyle

README.md

@@ -75,6 +75,6 @@ pip install --upgrade git+https://github.com/PaddlePaddle/PARL.git
 # Examples
 - [QuickStart](examples/QuickStart/)
 - [DQN](examples/DQN/)
-- DDPG
+- [DDPG](examples/DDPG/)
 - PPO
 - [Winning Solution for NIPS2018: AI for Prosthetics Challenge](examples/NeurIPS2018-AI-for-Prosthetics-Challenge/)

examples/DDPG/README.md

+## Reproduce DDPG with PARL
+Based on PARL, the DDPG model of deep reinforcement learning is reproduced, and the same level of indicators of the paper is reproduced in the classic Mujoco game.
+
++ DDPG in
+[Continuous control with deep reinforcement learning](https://arxiv.org/abs/1509.02971)
+
+### Mujoco games introduction
+Please see [here](https://github.com/openai/mujoco-py) to know more about Mujoco game.
+
+
+## How to use
+### Dependencies:
++ python2.7 or python3.5+
++ [PARL](https://github.com/PaddlePaddle/PARL)
++ [paddlepaddle>=1.0.0](https://github.com/PaddlePaddle/Paddle)
++ gym
++ tqdm
++ mujoco-py>=1.50.1.0
+
+### Start Training:
+```
+# To train an agent for HalfCheetah-v2 game
+python train.py
+
+# To train for other game
+# python train.py --env [ENV_NAME]

examples/DDPG/mujoco_agent.py

+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import numpy as np
+import parl.layers as layers
+from paddle import fluid
+from parl.framework.agent_base import Agent
+
+
+class MujocoAgent(Agent):
+    def __init__(self, algorithm, obs_dim, act_dim):
+        self.obs_dim = obs_dim
+        self.act_dim = act_dim
+        super(MujocoAgent, self).__init__(algorithm)
+
+        # Attention: In the beginning, sync target model totally.
+        self.alg.sync_target(gpu_id=self.gpu_id, decay=0)
+
+    def build_program(self):
+        self.pred_program = fluid.Program()
+        self.learn_program = fluid.Program()
+
+        with fluid.program_guard(self.pred_program):
+            obs = layers.data(
+                name='obs', shape=[self.obs_dim], dtype='float32')
+            self.pred_act = self.alg.define_predict(obs)
+
+        with fluid.program_guard(self.learn_program):
+            obs = layers.data(
+                name='obs', shape=[self.obs_dim], dtype='float32')
+            act = layers.data(
+                name='act', shape=[self.act_dim], dtype='float32')
+            reward = layers.data(name='reward', shape=[], dtype='float32')
+            next_obs = layers.data(
+                name='next_obs', shape=[self.obs_dim], dtype='float32')
+            terminal = layers.data(name='terminal', shape=[], dtype='bool')
+            _, self.critic_cost = self.alg.define_learn(
+                obs, act, reward, next_obs, terminal)
+
+    def predict(self, obs):
+        obs = np.expand_dims(obs, axis=0)
+        act = self.fluid_executor.run(
+            self.pred_program, feed={'obs': obs},
+            fetch_list=[self.pred_act])[0]
+        return act
+
+    def learn(self, obs, act, reward, next_obs, terminal):
+        feed = {
+            'obs': obs,
+            'act': act,
+            'reward': reward,
+            'next_obs': next_obs,
+            'terminal': terminal
+        }
+        critic_cost = self.fluid_executor.run(
+            self.learn_program, feed=feed, fetch_list=[self.critic_cost])[0]
+        self.alg.sync_target(gpu_id=self.gpu_id)
+        return critic_cost

examples/DDPG/mujoco_model.py

+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import paddle.fluid as fluid
+import parl.layers as layers
+from parl.framework.model_base import Model
+
+
+class MujocoModel(Model):
+    def __init__(self, act_dim, act_bound):
+        self.actor_model = ActorModel(act_dim, act_bound)
+        self.critic_model = CriticModel()
+
+    def policy(self, obs):
+        return self.actor_model.policy(obs)
+
+    def value(self, obs, act):
+        return self.critic_model.value(obs, act)
+
+    def get_actor_params(self):
+        return self.actor_model.parameter_names
+
+
+class ActorModel(Model):
+    def __init__(self, act_dim, act_bound):
+        self.act_bound = act_bound
+        hid1_size = 400
+        hid2_size = 300
+
+        self.fc1 = layers.fc(size=hid1_size, act='relu')
+        self.fc2 = layers.fc(size=hid2_size, act='relu')
+        self.fc3 = layers.fc(size=act_dim, act='tanh')
+
+    def policy(self, obs):
+        hid1 = self.fc1(obs)
+        hid2 = self.fc2(hid1)
+        means = self.fc3(hid2)
+        means = means * self.act_bound
+        return means
+
+
+class CriticModel(Model):
+    def __init__(self):
+        hid1_size = 400
+        hid2_size = 300
+
+        self.fc1 = layers.fc(size=hid1_size, act='relu')
+        self.fc2 = layers.fc(size=hid2_size, act='relu')
+        self.fc3 = layers.fc(size=1, act=None)
+
+    def value(self, obs, act):
+        hid1 = self.fc1(obs)
+        concat = layers.concat([hid1, act], axis=1)
+        hid2 = self.fc2(concat)
+        Q = self.fc3(hid2)
+        Q = layers.squeeze(Q, axes=[1])
+        return Q

examples/DDPG/replay_memory.py

+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import numpy as np
+
+
+class ReplayMemory(object):
+    def __init__(self, max_size, obs_dim, act_dim):
+        self.max_size = max_size
+        self.obs_memory = np.zeros((max_size, obs_dim), dtype='float32')
+        self.act_memory = np.zeros((max_size, act_dim), dtype='float32')
+        self.reward_memory = np.zeros((max_size, ), dtype='float32')
+        self.next_obs_memory = np.zeros((max_size, obs_dim), dtype='float32')
+        self.terminal_memory = np.zeros((max_size, ), dtype='bool')
+        self._curr_size = 0
+        self._curr_pos = 0
+
+    def sample_batch(self, batch_size):
+        batch_idx = np.random.choice(self._curr_size, size=batch_size)
+        obs = self.obs_memory[batch_idx, :]
+        act = self.act_memory[batch_idx, :]
+        reward = self.reward_memory[batch_idx]
+        next_obs = self.next_obs_memory[batch_idx, :]
+        terminal = self.terminal_memory[batch_idx]
+        return obs, act, reward, next_obs, terminal
+
+    def append(self, obs, act, reward, next_obs, terminal):
+        if self._curr_size < self.max_size:
+            self._curr_size += 1
+        self.obs_memory[self._curr_pos] = obs
+        self.act_memory[self._curr_pos] = act
+        self.reward_memory[self._curr_pos] = reward
+        self.next_obs_memory[self._curr_pos] = next_obs
+        self.terminal_memory[self._curr_pos] = terminal
+        self._curr_pos = (self._curr_pos + 1) % self.max_size
+
+    def size(self):
+        return self._curr_size

examples/DDPG/train.py

+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import argparse
+import gym
+import numpy as np
+import time
+from mujoco_agent import MujocoAgent
+from mujoco_model import MujocoModel
+from parl.algorithms import DDPG
+from parl.utils import logger
+from replay_memory import ReplayMemory
+
+MAX_EPISODES = 5000
+TEST_EVERY_EPISODES = 50
+MAX_STEPS_EACH_EPISODE = 1000
+ACTOR_LR = 1e-4
+CRITIC_LR = 1e-3
+GAMMA = 0.99
+TAU = 0.001
+MEMORY_SIZE = int(1e6)
+MIN_LEARN_SIZE = 1e4
+BATCH_SIZE = 128
+REWARD_SCALE = 0.1
+ENV_SEED = 1
+
+
+def run_train_episode(env, agent, rpm, act_bound):
+    obs = env.reset()
+    total_reward = 0
+    for j in range(MAX_STEPS_EACH_EPISODE):
+        batch_obs = np.expand_dims(obs, axis=0)
+        action = agent.predict(batch_obs.astype('float32'))
+        action = np.squeeze(action)
+
+        # Add exploration noise
+        action = np.clip(
+            np.random.normal(action, act_bound), -act_bound, act_bound)
+
+        next_obs, reward, done, info = env.step(action)
+
+        rpm.append(obs, action, REWARD_SCALE * reward, next_obs, done)
+
+        if rpm.size() > MIN_LEARN_SIZE:
+            batch_obs, batch_action, batch_reward, batch_next_obs, batch_terminal = rpm.sample_batch(
+                BATCH_SIZE)
+            agent.learn(batch_obs, batch_action, batch_reward, batch_next_obs,
+                        batch_terminal)
+
+        obs = next_obs
+        total_reward += reward
+
+        if done:
+            break
+    return total_reward
+
+
+def run_evaluate_episode(env, agent):
+    obs = env.reset()
+    total_reward = 0
+    for j in range(MAX_STEPS_EACH_EPISODE):
+        batch_obs = np.expand_dims(obs, axis=0)
+        action = agent.predict(batch_obs.astype('float32'))
+        action = np.squeeze(action)
+
+        next_obs, reward, done, info = env.step(action)
+
+        obs = next_obs
+        total_reward += reward
+
+        if done:
+            break
+    return total_reward
+
+
+def main():
+    env = gym.make(args.env)
+    env.seed(ENV_SEED)
+
+    obs_dim = env.observation_space.shape[0]
+    act_dim = env.action_space.shape[0]
+    act_bound = env.action_space.high[0]
+
+    model = MujocoModel(act_dim, act_bound)
+    algorithm = DDPG(
+        model,
+        hyperparas={
+            'gamma': GAMMA,
+            'tau': TAU,
+            'actor_lr': ACTOR_LR,
+            'critic_lr': CRITIC_LR
+        })
+    agent = MujocoAgent(algorithm, obs_dim, act_dim)
+
+    rpm = ReplayMemory(MEMORY_SIZE, obs_dim, act_dim)
+
+    for i in range(MAX_EPISODES):
+        train_reward = run_train_episode(env, agent, rpm, act_bound)
+        logger.info('Episode: {} Reward: {}'.format(i, train_reward))
+        if (i + 1) % TEST_EVERY_EPISODES == 0:
+            evaluate_reward = run_evaluate_episode(env, agent)
+            logger.info('Evaluate Reward: {}'.format(evaluate_reward))
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        '--env', help='Mujoco environment name', default='HalfCheetah-v2')
+    args = parser.parse_args()
+    main()

examples/DQN/atari_agent.py

@@ -32,7 +32,7 @@ class AtariAgent(Agent):
 
     def build_program(self):
         self.pred_program = fluid.Program()
-        self.train_program = fluid.Program()
+        self.learn_program = fluid.Program()
 
         with fluid.program_guard(self.pred_program):
             obs = layers.data(
@@ -41,7 +41,7 @@ class AtariAgent(Agent):
                 dtype='float32')
             self.value = self.alg.define_predict(obs)
 
-        with fluid.program_guard(self.train_program):
+        with fluid.program_guard(self.learn_program):
             obs = layers.data(
                 name='obs',
                 shape=[CONTEXT_LEN, IMAGE_SIZE[0], IMAGE_SIZE[1]],
@@ -99,5 +99,5 @@ class AtariAgent(Agent):
             'terminal': terminal
         }
         cost = self.fluid_executor.run(
-            self.train_program, feed=feed, fetch_list=[self.cost])[0]
+            self.learn_program, feed=feed, fetch_list=[self.cost])[0]
         return cost

examples/DQN/atari_model.py

@@ -18,9 +18,7 @@ from parl.framework.model_base import Model
 
 
 class AtariModel(Model):
-    def __init__(self, img_height, img_width, act_dim):
-        self.img_height = img_height
-        self.img_width = img_width
+    def __init__(self, act_dim):
         self.act_dim = act_dim
 
         self.conv1 = layers.conv2d(

examples/DQN/expreplay.py → examples/DQN/replay_memory.py

@@ -88,6 +88,9 @@ class ReplayMemory(object):
     def __len__(self):
         return self._curr_size
 
+    def size(self):
+        return self._curr_size
+
     def _assign(self, pos, exp):
         self.state[pos] = exp.state
         self.reward[pos] = exp.reward

examples/DQN/train.py

@@ -13,49 +13,47 @@
 # limitations under the License.
 
 import argparse
-import cv2
 import gym
 import paddle.fluid as fluid
 import numpy as np
 import os
-from atari import AtariPlayer
 from atari_agent import AtariAgent
 from atari_model import AtariModel
-from atari_wrapper import FrameStack, MapState, FireResetEnv, LimitLength
 from collections import deque
 from datetime import datetime
-from expreplay import ReplayMemory, Experience
+from replay_memory import ReplayMemory, Experience
 from parl.algorithms import DQN
 from parl.utils import logger
 from tqdm import tqdm
+from utils import get_player
 
 MEMORY_SIZE = 1e6
 MEMORY_WARMUP_SIZE = MEMORY_SIZE // 20
 IMAGE_SIZE = (84, 84)
 CONTEXT_LEN = 4
-ACTION_REPEAT = 4  # aka FRAME_SKIP
+FRAME_SKIP = 4
 UPDATE_FREQ = 4
 GAMMA = 0.99
 LEARNING_RATE = 1e-3 * 0.5
 
 
-def run_train_episode(agent, env, exp):
+def run_train_episode(env, agent, rpm):
     total_reward = 0
     all_cost = []
     state = env.reset()
     step = 0
     while True:
         step += 1
-        context = exp.recent_state()
+        context = rpm.recent_state()
         context.append(state)
         context = np.stack(context, axis=0)
         action = agent.sample(context)
         next_state, reward, isOver, _ = env.step(action)
-        exp.append(Experience(state, action, reward, isOver))
+        rpm.append(Experience(state, action, reward, isOver))
         # start training
-        if len(exp) > MEMORY_WARMUP_SIZE:
+        if rpm.size() > MEMORY_WARMUP_SIZE:
             if step % UPDATE_FREQ == 0:
-                batch_all_state, batch_action, batch_reward, batch_isOver = exp.sample_batch(
+                batch_all_state, batch_action, batch_reward, batch_isOver = rpm.sample_batch(
                     args.batch_size)
                 batch_state = batch_all_state[:, :CONTEXT_LEN, :, :]
                 batch_next_state = batch_all_state[:, 1:, :, :]
@@ -71,43 +69,27 @@ def run_train_episode(agent, env, exp):
     return total_reward, step
 
 
-def get_player(rom, viz=False, train=False):
-    env = AtariPlayer(
-        rom,
-        frame_skip=ACTION_REPEAT,
-        viz=viz,
-        live_lost_as_eoe=train,
-        max_num_frames=60000)
-    env = FireResetEnv(env)
-    env = MapState(env, lambda im: cv2.resize(im, IMAGE_SIZE))
-    if not train:
-        # in training, context is taken care of in expreplay buffer
-        env = FrameStack(env, CONTEXT_LEN)
-    return env
-
-
-def eval_agent(agent, env):
-    episode_reward = []
-    for _ in tqdm(range(30), desc='eval agent'):
-        state = env.reset()
-        total_reward = 0
-        step = 0
-        while True:
-            step += 1
-            action = agent.predict(state)
-            state, reward, isOver, info = env.step(action)
-            total_reward += reward
-            if isOver:
-                break
-        episode_reward.append(total_reward)
-    eval_reward = np.mean(episode_reward)
-    return eval_reward
-
-
-def train_agent():
-    env = get_player(args.rom, train=True)
-    test_env = get_player(args.rom)
-    exp = ReplayMemory(MEMORY_SIZE, IMAGE_SIZE, CONTEXT_LEN)
+def run_evaluate_episode(env, agent):
+    state = env.reset()
+    total_reward = 0
+    while True:
+        action = agent.predict(state)
+        state, reward, isOver, info = env.step(action)
+        total_reward += reward
+        if isOver:
+            break
+    return total_reward
+
+
+def main():
+    env = get_player(
+        args.rom, image_size=IMAGE_SIZE, train=True, frame_skip=FRAME_SKIP)
+    test_env = get_player(
+        args.rom,
+        image_size=IMAGE_SIZE,
+        frame_skip=FRAME_SKIP,
+        context_len=CONTEXT_LEN)
+    rpm = ReplayMemory(MEMORY_SIZE, IMAGE_SIZE, CONTEXT_LEN)
     action_dim = env.action_space.n
 
     hyperparas = {
@@ -115,13 +97,13 @@ def train_agent():
         'lr': LEARNING_RATE,
         'gamma': GAMMA
     }
-    model = AtariModel(IMAGE_SIZE[0], IMAGE_SIZE[1], action_dim)
+    model = AtariModel(action_dim)
     algorithm = DQN(model, hyperparas)
     agent = AtariAgent(algorithm, action_dim)
 
     with tqdm(total=MEMORY_WARMUP_SIZE) as pbar:
-        while len(exp) < MEMORY_WARMUP_SIZE:
-            total_reward, step = run_train_episode(agent, env, exp)
+        while rpm.size() < MEMORY_WARMUP_SIZE:
+            total_reward, step = run_train_episode(env, agent, rpm)
             pbar.update(step)
 
     # train
@@ -132,18 +114,23 @@ def train_agent():
     max_reward = None
     while True:
         # start epoch
-        total_reward, step = run_train_episode(agent, env, exp)
+        total_reward, step = run_train_episode(env, agent, rpm)
         total_step += step
         pbar.set_description('[train]exploration:{}'.format(agent.exploration))
         pbar.update(step)
 
         if total_step // args.test_every_steps == test_flag:
             pbar.write("testing")
-            eval_reward = eval_agent(agent, test_env)
+            eval_rewards = []
+            for _ in tqdm(range(30), desc='eval agent'):
+                eval_reward = run_evaluate_episode(test_env, agent)
+                eval_rewards.append(eval_reward)
             test_flag += 1
             logger.info(
                 "eval_agent done, (steps, eval_reward): ({}, {})".format(
-                    total_step, eval_reward))
+                    total_step, np.mean(eval_rewards)))
+        if total_step > 1e8:
+            break
 
     pbar.close()
 
@@ -159,4 +146,4 @@ if __name__ == '__main__':
         default=100000,
         help='every steps number to run test')
     args = parser.parse_args()
-    train_agent()
+    main()

examples/DQN/utils.py

+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import cv2
+from atari import AtariPlayer
+from atari_wrapper import FrameStack, MapState, FireResetEnv
+
+
+def get_player(rom,
+               image_size,
+               viz=False,
+               train=False,
+               frame_skip=1,
+               context_len=1):
+    env = AtariPlayer(
+        rom,
+        frame_skip=frame_skip,
+        viz=viz,
+        live_lost_as_eoe=train,
+        max_num_frames=60000)
+    env = FireResetEnv(env)
+    env = MapState(env, lambda im: cv2.resize(im, image_size))
+    if not train:
+        # in training, context is taken care of in expreplay buffer
+        env = FrameStack(env, context_len)
+    return env

examples/QuickStart/README.md

@@ -24,6 +24,7 @@ pip install .
 cd examples/QuickStart/
 python train.py  
 # Or visualize when evaluating: python train.py --eval_vis
+```
 
 ### Result
 After training, you will see the agent get the best score (200 points).

examples/QuickStart/cartpole_agent.py

@@ -19,15 +19,19 @@ from parl.framework.agent_base import Agent
 
 
 class CartpoleAgent(Agent):
-    def __init__(self, algorithm, obs_dim, act_dim):
+    def __init__(self, algorithm, obs_dim, act_dim, seed=1):
         self.obs_dim = obs_dim
         self.act_dim = act_dim
+        self.seed = seed
         super(CartpoleAgent, self).__init__(algorithm)
 
     def build_program(self):
         self.pred_program = fluid.Program()
         self.train_program = fluid.Program()
 
+        fluid.default_startup_program().random_seed = self.seed
+        self.train_program.random_seed = self.seed
+
         with fluid.program_guard(self.pred_program):
             obs = layers.data(
                 name='obs', shape=[self.obs_dim], dtype='float32')

examples/QuickStart/train.py

@@ -19,11 +19,13 @@ from cartpole_agent import CartpoleAgent
 from cartpole_model import CartpoleModel
 from parl.algorithms import PolicyGradient
 from parl.utils import logger
+from utils import calc_discount_norm_reward
 
 OBS_DIM = 4
 ACT_DIM = 2
 GAMMA = 0.99
 LEARNING_RATE = 1e-3
+SEED = 1
 
 
 def run_train_episode(env, agent):
@@ -56,32 +58,21 @@ def run_evaluate_episode(env, agent):
     return all_reward
 
 
-def calc_discount_norm_reward(reward_list):
-    discount_norm_reward = np.zeros_like(reward_list)
-
-    discount_cumulative_reward = 0
-    for i in reversed(range(0, len(reward_list))):
-        discount_cumulative_reward = (
-            GAMMA * discount_cumulative_reward + reward_list[i])
-        discount_norm_reward[i] = discount_cumulative_reward
-    discount_norm_reward = discount_norm_reward - np.mean(discount_norm_reward)
-    discount_norm_reward = discount_norm_reward / np.std(discount_norm_reward)
-    return discount_norm_reward
-
-
 def main():
     env = gym.make("CartPole-v0")
+    env.seed(SEED)
+    np.random.seed(SEED)
     model = CartpoleModel(act_dim=ACT_DIM)
     alg = PolicyGradient(model, hyperparas={'lr': LEARNING_RATE})
-    agent = CartpoleAgent(alg, obs_dim=OBS_DIM, act_dim=ACT_DIM)
+    agent = CartpoleAgent(alg, obs_dim=OBS_DIM, act_dim=ACT_DIM, seed=SEED)
 
-    for i in range(500):
+    for i in range(1000):
         obs_list, action_list, reward_list = run_train_episode(env, agent)
         logger.info("Episode {}, Reward Sum {}.".format(i, sum(reward_list)))
 
         batch_obs = np.array(obs_list)
         batch_action = np.array(action_list)
-        batch_reward = calc_discount_norm_reward(reward_list)
+        batch_reward = calc_discount_norm_reward(reward_list, GAMMA)
 
         agent.learn(batch_obs, batch_action, batch_reward)
         if (i + 1) % 100 == 0:

examples/QuickStart/utils.py

+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import numpy as np
+
+
+def calc_discount_norm_reward(reward_list, gamma):
+    discount_norm_reward = np.zeros_like(reward_list)
+
+    discount_cumulative_reward = 0
+    for i in reversed(range(0, len(reward_list))):
+        discount_cumulative_reward = (
+            gamma * discount_cumulative_reward + reward_list[i])
+        discount_norm_reward[i] = discount_cumulative_reward
+    discount_norm_reward = discount_norm_reward - np.mean(discount_norm_reward)
+    discount_norm_reward = discount_norm_reward / np.std(discount_norm_reward)
+    return discount_norm_reward

parl/algorithms/__init__.py

@@ -14,3 +14,4 @@
 
 from parl.algorithms.dqn import *
 from parl.algorithms.policy_gradient import *
+from parl.algorithms.ddpg import *

parl/algorithms/ddpg.py

+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import parl.layers as layers
+from copy import deepcopy
+from paddle import fluid
+from parl.framework.algorithm_base import Algorithm
+
+__all__ = ['DDPG']
+
+
+class DDPG(Algorithm):
+    def __init__(self, model, hyperparas):
+        """ model: should implement the function get_actor_params()
+        """
+        Algorithm.__init__(self, model, hyperparas)
+        self.model = model
+        self.target_model = deepcopy(model)
+
+        # fetch hyper parameters
+        self.gamma = hyperparas['gamma']
+        self.tau = hyperparas['tau']
+        self.actor_lr = hyperparas['actor_lr']
+        self.critic_lr = hyperparas['critic_lr']
+
+    def define_predict(self, obs):
+        """ use actor model of self.model to predict the action
+        """
+        return self.model.policy(obs)
+
+    def define_learn(self, obs, action, reward, next_obs, terminal):
+        """ update actor and critic model with DDPG algorithm
+        """
+        actor_cost = self._actor_learn(obs)
+        critic_cost = self._critic_learn(obs, action, reward, next_obs,
+                                         terminal)
+        return actor_cost, critic_cost
+
+    def _actor_learn(self, obs):
+        action = self.model.policy(obs)
+        Q = self.model.value(obs, action)
+        cost = layers.reduce_mean(-1.0 * Q)
+        optimizer = fluid.optimizer.AdamOptimizer(self.actor_lr)
+        optimizer.minimize(cost, parameter_list=self.model.get_actor_params())
+        return cost
+
+    def _critic_learn(self, obs, action, reward, next_obs, terminal):
+        next_action = self.target_model.policy(next_obs)
+        next_Q = self.target_model.value(next_obs, next_action)
+
+        terminal = layers.cast(terminal, dtype='float32')
+        target_Q = reward + (1.0 - terminal) * self.gamma * next_Q
+        target_Q.stop_gradient = True
+
+        Q = self.model.value(obs, action)
+        cost = layers.square_error_cost(Q, target_Q)
+        cost = layers.reduce_mean(cost)
+        optimizer = fluid.optimizer.AdamOptimizer(self.critic_lr)
+        optimizer.minimize(cost)
+        return cost
+
+    def sync_target(self, gpu_id, decay=None):
+        if decay is None:
+            decay = 1.0 - self.tau
+        self.model.sync_params_to(
+            self.target_model, gpu_id=gpu_id, decay=decay)

parl/utils/gputils.py

@@ -32,19 +32,21 @@ def get_gpu_count():
     if env_cuda_devices is not None:
         assert isinstance(env_cuda_devices, str)
         try:
+            if not env_cuda_devices:
+                return 0
             gpu_count = len(
                 [x for x in env_cuda_devices.split(',') if int(x) >= 0])
             logger.info(
                 'CUDA_VISIBLE_DEVICES found gpu count: {}'.format(gpu_count))
-        except Exception as e:
-            logger.error(e.message)
+        except:
+            logger.warn('Cannot find available GPU devices, using CPU now.')
             gpu_count = 0
     else:
         try:
             gpu_count = str(subprocess.check_output(["nvidia-smi",
                                                      "-L"])).count('UUID')
             logger.info('nvidia-smi -L found gpu count: {}'.format(gpu_count))
-        except Exception as e:
-            logger.error(e.message)
+        except:
+            logger.warn('Cannot find available GPU devices, using CPU now.')
             gpu_count = 0
     return gpu_count