Simple Implementation of ICM

Author: philtabor

ReinforcementLearning/ICM/A3C_CartPole_no_rewards.png

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+import numpy as np
+import torch as T
+import torch.nn as nn
+import torch.nn.functional as F
+from torch.distributions import Categorical
+
+
+class ActorCritic(nn.Module):
+    def __init__(self, input_dims, n_actions, gamma=0.99, tau=0.98):
+        super(ActorCritic, self).__init__()
+        self.gamma = gamma
+        self.tau = tau
+
+        self.input = nn.Linear(*input_dims, 256)
+        self.dense = nn.Linear(256, 256)
+
+        self.gru = nn.GRUCell(256, 256)
+        self.pi = nn.Linear(256, n_actions)
+        self.v = nn.Linear(256, 1)
+
+    def forward(self, state, hx):
+        x = F.relu(self.input(state))
+        x = F.relu(self.dense(x))
+        hx = self.gru(x, (hx))
+
+        pi = self.pi(hx)
+        v = self.v(hx)
+
+        probs = T.softmax(pi, dim=1)
+        dist = Categorical(probs)
+        action = dist.sample()
+        log_prob = dist.log_prob(action)
+
+        return action.numpy()[0], v, log_prob, hx
+
+    def calc_R(self, done, rewards, values):
+        values = T.cat(values).squeeze()
+        if len(values.size()) == 1:  # batch of states
+            R = values[-1] * (1-int(done))
+        elif len(values.size()) == 0:  # single state
+            R = values*(1-int(done))
+
+        batch_return = []
+        for reward in rewards[::-1]:
+            R = reward + self.gamma * R
+            batch_return.append(R)
+        batch_return.reverse()
+        batch_return = T.tensor(batch_return, 
+                                dtype=T.float).reshape(values.size())
+        return batch_return
+
+    def calc_loss(self, new_states, hx, done,
+                  rewards, values, log_probs, r_i_t=None):
+        if r_i_t is not None:
+            rewards += r_i_t.detach().numpy()
+        returns = self.calc_R(done, rewards, values)
+        next_v = T.zeros(1, 1) if done else self.forward(T.tensor([new_states],
+                                         dtype=T.float), hx)[1]
+
+        values.append(next_v.detach())
+        values = T.cat(values).squeeze()
+        log_probs = T.cat(log_probs)
+        rewards = T.tensor(rewards)
+
+        delta_t = rewards + self.gamma*values[1:] - values[:-1]
+        n_steps = len(delta_t)
+        gae = np.zeros(n_steps)
+        for t in range(n_steps):
+            for k in range(0, n_steps-t):
+                temp = (self.gamma*self.tau)**k*delta_t[t+k]
+                gae[t] += temp
+        gae = T.tensor(gae, dtype=T.float)
+
+        actor_loss = -(log_probs*gae).sum()
+        entropy_loss = (-log_probs*T.exp(log_probs)).sum()
+        # [T] vs ()
+        critic_loss = F.mse_loss(values[:-1].squeeze(), returns)
+
+        total_loss = actor_loss + critic_loss - 0.01*entropy_loss
+        return total_loss

ReinforcementLearning/ICM/ICM_CartPole_no_rewards.png

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+import torch as T
+import torch.nn as nn
+import torch.nn.functional as F
+
+
+class ICM(nn.Module):
+    def __init__(self, input_dims, n_actions=2, alpha=1, beta=0.2):
+        super(ICM, self).__init__()
+        self.alpha = alpha
+        self.beta = beta
+        # hard coded for cartpole environment
+        self.inverse = nn.Linear(4*2, 256)
+        self.pi_logits = nn.Linear(256, n_actions)
+
+        self.dense1 = nn.Linear(4+1, 256)
+        self.new_state = nn.Linear(256, 4)
+
+        device = T.device('cpu')
+        self.to(device)
+
+    def forward(self, state, new_state, action):
+        inverse = F.elu(self.inverse(T.cat([state, new_state], dim=1)))
+        pi_logits = self.pi_logits(inverse)
+
+        # from [T] to [T,1]
+        action = action.reshape((action.size()[0], 1))
+        forward_input = T.cat([state, action], dim=1)
+        dense = F.elu(self.dense1(forward_input))
+        state_ = self.new_state(dense)
+
+        return pi_logits, state_
+
+    def calc_loss(self, state, new_state, action):
+        state = T.tensor(state, dtype=T.float)
+        action = T.tensor(action, dtype=T.float)
+        new_state = T.tensor(new_state, dtype=T.float)
+
+        pi_logits, state_ = self.forward(state, new_state, action)
+
+        inverse_loss = nn.CrossEntropyLoss()
+        L_I = (1-self.beta)*inverse_loss(pi_logits, action.to(T.long))
+
+        forward_loss = nn.MSELoss()
+        L_F = self.beta*forward_loss(state_, new_state)
+
+        intrinsic_reward = self.alpha*((state_ - new_state).pow(2)).mean(dim=1)
+        return intrinsic_reward, L_I, L_F

ReinforcementLearning/ICM/actor_critic.py

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+import os
+import torch.multiprocessing as mp
+from parallel_env import ParallelEnv
+
+os.environ['OMP_NUM_THREADS'] = '1'
+
+
+if __name__ == '__main__':
+    mp.set_start_method('spawn')
+    env_id = 'CartPole-v0'
+    n_threads = 12
+    n_actions = 2
+    input_shape = [4]
+    env = ParallelEnv(env_id=env_id, n_threads=n_threads,
+                      n_actions=n_actions, input_shape=input_shape, icm=True)

ReinforcementLearning/ICM/icm.py

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+class Memory:
+    def __init__(self):
+        self.states = []
+        self.actions = []
+        self.rewards = []
+        self.new_states = []
+        self.values = []
+        self.log_probs = []
+
+    def remember(self, state, action, reward, new_state, value, log_p):
+        self.actions.append(action)
+        self.rewards.append(reward)
+        self.states.append(state)
+        self.new_states.append(new_state)
+        self.log_probs.append(log_p)
+        self.values.append(value)
+
+    def clear_memory(self):
+        self.states = []
+        self.actions = []
+        self.rewards = []
+        self.new_states = []
+        self.values = []
+        self.log_probs = []
+
+    def sample_memory(self):
+        return self.states, self.actions, self.rewards, self.new_states,\
+               self.values, self.log_probs

ReinforcementLearning/ICM/main.py

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+import torch.multiprocessing as mp
+from actor_critic import ActorCritic
+from icm import ICM
+from shared_adam import SharedAdam
+from worker import worker
+
+
+class ParallelEnv:
+    def __init__(self, env_id, input_shape, n_actions, icm, n_threads=8):
+        names = [str(i) for i in range(1, n_threads+1)]
+
+        global_actor_critic = ActorCritic(input_shape, n_actions)
+        global_actor_critic.share_memory()
+        global_optim = SharedAdam(global_actor_critic.parameters())
+
+        if not icm:
+            global_icm = None
+            global_icm_optim = None
+        else:
+            global_icm = ICM(input_shape, n_actions)
+            global_icm.share_memory()
+            global_icm_optim = SharedAdam(global_icm.parameters())
+
+        self.ps = [mp.Process(target=worker,
+                              args=(name, input_shape, n_actions,
+                                    global_actor_critic, global_icm,
+                                    global_optim, global_icm_optim, env_id,
+                                    n_threads, icm))
+                   for name in names]
+
+        [p.start() for p in self.ps]
+        [p.join() for p in self.ps]

ReinforcementLearning/ICM/memory.py

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+import torch as T
+
+
+class SharedAdam(T.optim.Adam):
+    def __init__(self, params, lr=1e-4, betas=(0.9, 0.99), eps=1e-8,
+                 weight_decay=0):
+        super(SharedAdam, self).__init__(params, lr=lr, betas=betas,
+                                         eps=eps, weight_decay=weight_decay)
+
+        for group in self.param_groups:
+            for p in group['params']:
+                state = self.state[p]
+                state['step'] = 0
+                state['exp_avg'] = T.zeros_like(p.data)
+                state['exp_avg_sq'] = T.zeros_like(p.data)
+
+                state['exp_avg'].share_memory_()
+                state['exp_avg_sq'].share_memory_()

ReinforcementLearning/ICM/parallel_env.py

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+import matplotlib.pyplot as plt
+import numpy as np
+
+
+def plot_learning_curve(x, scores, figure_file):
+    running_avg = np.zeros(len(scores))
+    for i in range(len(running_avg)):
+        running_avg[i] = np.mean(scores[max(0, i-100):(i+1)])
+    plt.plot(x, running_avg)
+    plt.title('Running average of previous 100 episodes')
+    plt.savefig(figure_file)

ReinforcementLearning/ICM/shared_adam.py

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+import gym
+import numpy as np
+import torch as T
+from actor_critic import ActorCritic
+from icm import ICM
+from memory import Memory
+from utils import plot_learning_curve
+
+
+def worker(name, input_shape, n_actions, global_agent, global_icm,
+           optimizer, icm_optimizer, env_id, n_threads, icm=False):
+    T_MAX = 20
+
+    local_agent = ActorCritic(input_shape, n_actions)
+
+    if icm:
+        local_icm = ICM(input_shape, n_actions)
+        algo = 'ICM'
+    else:
+        intrinsic_reward = T.zeros(1)
+        algo = 'A3C'
+
+    memory = Memory()
+
+    env = gym.make(env_id)
+
+    t_steps, max_eps, episode, scores, avg_score = 0, 1000, 0, [], 0
+
+    while episode < max_eps:
+        obs = env.reset()
+        hx = T.zeros(1, 256)
+        score, done, ep_steps = 0, False, 0
+        while not done:
+            state = T.tensor([obs], dtype=T.float)
+            action, value, log_prob, hx = local_agent(state, hx)
+            obs_, reward, done, info = env.step(action)
+            t_steps += 1
+            ep_steps += 1
+            score += reward
+            reward = 0  # turn off extrinsic rewards
+            memory.remember(obs, action, reward, obs_, value, log_prob)
+            obs = obs_
+            if ep_steps % T_MAX == 0 or done:
+                states, actions, rewards, new_states, values, log_probs = \
+                        memory.sample_memory()
+                if icm:
+                    intrinsic_reward, L_I, L_F = \
+                            local_icm.calc_loss(states, new_states, actions)
+
+                loss = local_agent.calc_loss(obs, hx, done, rewards, values,
+                                             log_probs, intrinsic_reward)
+
+                optimizer.zero_grad()
+                hx = hx.detach_()
+                if icm:
+                    icm_optimizer.zero_grad()
+                    (L_I + L_F).backward()
+
+                loss.backward()
+                T.nn.utils.clip_grad_norm_(local_agent.parameters(), 40)
+
+                for local_param, global_param in zip(
+                                        local_agent.parameters(),
+                                        global_agent.parameters()):
+                    global_param._grad = local_param.grad
+                optimizer.step()
+                local_agent.load_state_dict(global_agent.state_dict())
+
+                if icm:
+                    for local_param, global_param in zip(
+                                            local_icm.parameters(),
+                                            global_icm.parameters()):
+                        global_param._grad = local_param.grad
+                    icm_optimizer.step()
+                    local_icm.load_state_dict(global_icm.state_dict())
+                memory.clear_memory()
+
+        if name == '1':
+            scores.append(score)
+            avg_score = np.mean(scores[-100:])
+            print('{} episode {} thread {} of {} steps {:.2f}M score {:.2f} '
+                  'intrinsic_reward {:.2f} avg score (100) {:.1f}'.format(
+                      algo, episode, name, n_threads,
+                      t_steps/1e6, score,
+                      T.sum(intrinsic_reward),
+                      avg_score))
+        episode += 1
+    if name == '1':
+        x = [z for z in range(episode)]
+        fname = algo + '_CartPole_no_rewards.png'
+        plot_learning_curve(x, scores, fname)