def dyke_dqn_agent(env: TFPyEnvironment,
layers: Optional[List[Layer]] = None) -> DqnAgent:
"""
Prepares a deep Q-network (DQN) agent for use in the dyke maintenance environment.
:param env: The dyke environment on which to base the DQN agent.
:param layers: Optional. A list of layers to supply to the DQN agent's network.
:return: The agent.
"""
layers = fully_connected_dyke_dqn_agent_network(
sizes=(100, 50)) if layers is None else layers
# prepare the Q-values layer
action_as: BoundedArraySpec = from_spec(env.action_spec())
number_actions: int = int(action_as.maximum - action_as.minimum + 1)
q_values_layer: Layer = Dense(units=number_actions,
activation=None,
kernel_initializer=RandomUniform(
minval=-3e-3, maxval=3e-3),
bias_initializer=Constant(-2e-1))
net = Sequential(layers=layers + [q_values_layer])
# instantiate and return the agent
optimizer = Adam(learning_rate=1e-3)
train_step_counter = Variable(initial_value=0)
return DqnAgent(time_step_spec=env.time_step_spec(),
action_spec=env.action_spec(),
q_network=net,
optimizer=optimizer,
epsilon_greedy=0.1,
td_errors_loss_fn=element_wise_squared_loss,
train_step_counter=train_step_counter)
def create_dqn_agent(env, q_net):
# see TF-agents issue #113
#optimizer = keras.optimizers.RMSprop(lr=2.5e-4, rho=0.95, momentum=0.0,
# epsilon=0.00001, centered=True)
train_step = tf.Variable(0)
update_period = config.UPDATE_PERIOD # run a training step every 4 collect steps
optimizer = tf.compat.v1.train.RMSPropOptimizer(learning_rate=2.5e-4,
decay=0.95,
momentum=0.0,
epsilon=0.00001,
centered=True)
epsilon_fn = keras.optimizers.schedules.PolynomialDecay(
initial_learning_rate=1.0, # initial ε
decay_steps=250000 // update_period, # <=> 1,000,000 ALE frames
end_learning_rate=0.01) # final ε
agent = DqnAgent(
env.time_step_spec(),
env.action_spec(),
q_network=q_net,
optimizer=optimizer,
target_update_period=2000, # <=> 32,000 ALE frames
td_errors_loss_fn=keras.losses.Huber(reduction="none"),
gamma=0.99, # discount factor
train_step_counter=train_step,
epsilon_greedy=lambda: epsilon_fn(train_step))
return agent
def compile(self, X_train: np.ndarray, y_train: np.ndarray, lr: float, epsilon: float, gamma: float, imb_ratio: float,
replay_buffer_max_length: int, layers: dict) -> None:
"""
Create the Q-network, agent and policy
Args:
X_train: A np.ndarray for training samples.
y_train: A np.ndarray for the class labels of the training samples.
lr: learn rate for the optimizer (default Adam)
epsilon: Used for the default epsilon greedy policy for choosing a random action.
gamma: The discount factor for learning Q-values
imb_ratio: ratio of imbalance. Used to specifiy reward in the environment
replay_buffer_max_length: Maximum lenght of replay memory.
layers: A dict containing the layers of the Q-Network (eg, conv, dense, rnn, dropout).
"""
dense_layers = layers.get("dense")
conv_layers = layers.get("conv")
dropout_layers = layers.get("dropout")
self.train_env = TFPyEnvironment(ClassifyEnv(X_train, y_train, imb_ratio)) # create a custom environment
q_net = QNetwork(self.train_env.observation_spec(), self.train_env.action_spec(), conv_layer_params=conv_layers,
fc_layer_params=dense_layers, dropout_layer_params=dropout_layers)
optimizer = tf.compat.v1.train.AdamOptimizer(learning_rate=lr)
train_step_counter = tf.Variable(0)
self.agent = DqnAgent(
self.train_env.time_step_spec(),
self.train_env.action_spec(),
q_network=q_net,
optimizer=optimizer,
td_errors_loss_fn=common.element_wise_squared_loss,
train_step_counter=train_step_counter,
gamma=gamma,
epsilon_greedy=epsilon,
)
self.agent.initialize()
self.replay_buffer = TFUniformReplayBuffer(
data_spec=self.agent.collect_data_spec,
batch_size=self.train_env.batch_size,
max_length=replay_buffer_max_length)
def build_dqn_agent(self):
"""Build DQN agent with QNetwork."""
temp_env = self.build_temp_env()
q_net = q_network.QNetwork(
temp_env.observation_spec(),
temp_env.action_spec(),
fc_layer_params=self.fc_layer_params,
dropout_layer_params=self.dropout_layer_params)
optimizer = tf.keras.optimizers.Adam(learning_rate=self.learning_rate)
agent = DqnAgent(
temp_env.time_step_spec(),
temp_env.action_spec(),
n_step_update=self.n_step_update,
q_network=q_net,
optimizer=optimizer,
epsilon_greedy=self.epsilon_greedy,
td_errors_loss_fn=common.element_wise_squared_loss,
train_step_counter=tf.Variable(0, dtype=tf.int64))
return q_net, agent
def train_model(self):
train_step = tf.Variable(0) # count num of training steps
update_period = 4 # train the model every 4 steps
optimizer = keras.optimizers.RMSprop(lr=2.5e-4,
rho=0.95,
momentum=0.0,
epsilon=0.00001,
centered=True)
epsilon_fn = keras.optimizers.schedules.PolynomialDecay(
initial_learning_rate=1.0, # initial ε
decay_steps=250000 // update_period, # <=> 1,000,000 ALE frames
end_learning_rate=0.01) # final ε
agent = DqnAgent(
self.tf_env.time_step_spec(),
self.tf_env.action_spec(),
q_network=self.q_net,
optimizer=optimizer,
target_update_period=2000, # <=> 32,000 ALE frames
td_errors_loss_fn=keras.losses.Huber(reduction="none"),
gamma=0.99, # discount factor
train_step_counter=train_step,
epsilon_greedy=lambda: epsilon_fn(train_step))
return agent
def create_pong_agent(train_environment: TFEnvironment,
dense_layer_sizes: Sequence[int],
learning_rate: float) -> (DqnAgent, QNetwork):
optimizer = tf.keras.optimizers.Adam(learning_rate=learning_rate)
global_step = tf.compat.v1.train.get_or_create_global_step()
q_net = QNetwork(input_tensor_spec=train_environment.observation_spec(),
action_spec=train_environment.action_spec(),
fc_layer_params=dense_layer_sizes)
agent = DqnAgent(time_step_spec=train_environment.time_step_spec(),
action_spec=train_environment.action_spec(),
q_network=q_net,
optimizer=optimizer,
td_errors_loss_fn=element_wise_squared_loss,
train_step_counter=global_step)
agent.initialize()
agent.train = common.function(agent.train)
agent.train_step_counter.assign(0)
return agent
learning_rate=optimizer_learning_rate,
decay=optimizer_decay,
momentum=optimizer_momentum,
epsilon=optimizer_epsilon,
centered=True)
# Computes epsilon for epsilon greedy policy given the training step
epsilon_fn = keras.optimizers.schedules.PolynomialDecay(
initial_learning_rate=1.0, # initial ε
decay_steps=epsilon_decay_steps,
end_learning_rate=epsilon_final) # final ε
agent = DqnAgent(
tf_env.time_step_spec(),
tf_env.action_spec(),
q_network=q_net,
optimizer=optimizer,
target_update_period=target_update_period,
td_errors_loss_fn=keras.losses.Huber(reduction="none"),
gamma=discount_factor, # discount factor
train_step_counter=train_step,
epsilon_greedy=lambda: epsilon_fn(train_step))
agent.initialize()
# Speed up as tensorflow function
agent.train = function(agent.train)
## ------------------------------------------------------------------------------
## ------------------------------------------------------------------------------
## ------------------------------------------------------------------------------
replay_buffer = tf_uniform_replay_buffer.TFUniformReplayBuffer(
# Determines the data spec type
data_spec=agent.collect_data_spec,
tf_env.observation_spec(),
tf_env.action_spec(),
preprocessing_layers=preprocessing_layer,
conv_layer_params=conv_layer_params,
fc_layer_params=fc_layer_params)
train_step = tf.Variable(0)
update_period = 4 # train the model every 4 steps
optimizer = keras.optimizers.RMSprop(lr=2.5e-4, rho=0.95, momentum=0.0, epsilon=0.00001, centered=True)
epsilon_fn = keras.optimizers.schedules.PolynomialDecay(initial_learning_rate=1.0, decay_steps= 250000, end_learning_rate=0.01)
agent = DqnAgent(tf_env.time_step_spec(),
tf_env.action_spec(),
q_network=q_net,
optimizer=optimizer,
target_update_period=2000,
td_errors_loss_fn=keras.losses.Huber(reduction='none'),
gamma=0.99,
train_step_counter=train_step,
epsilon_greedy=lambda: epsilon_fn(train_step))
agent.initialize()
replay_buffer = tf_uniform_replay_buffer.TFUniformReplayBuffer(
data_spec=agent.collect_data_spec,
batch_size=tf_env.batch_size,
max_length=850000)
replay_buffer_observer = replay_buffer.add_batch
def _init_qagent(self, optimizer, q_net, global_step):
args = self._get_agent_args(optimizer, q_net, global_step)
return DqnAgent(**args)
gym_env_wrappers=[ShrinkWrapper, DiscreteActionWrapper]))
# create DQN (deep Q-Learning network)
q_net = QNetwork(train_env.observation_spec(),
train_env.action_spec(),
conv_layer_params=conv_layer_params,
fc_layer_params=fc_layer_params)
optimizer = tf.compat.v1.train.AdamOptimizer(learning_rate=learning_rate)
train_step_counter = tf.compat.v2.Variable(0)
# create deep reinforcement learning agent
tf_agent = DqnAgent(train_env.time_step_spec(),
train_env.action_spec(),
q_network=q_net,
optimizer=optimizer,
td_errors_loss_fn=element_wise_squared_loss,
train_step_counter=train_step_counter)
tf_agent.initialize()
# create evaluation and data collection policies
eval_policy = tf_agent.policy
collect_policy = tf_agent.collect_policy
# create replay buffer
print("Creating replay buffer")
replay_buffer = TFUniformReplayBuffer(data_spec=tf_agent.collect_data_spec,
batch_size=train_env.batch_size,
max_length=replay_buffer_capacity)
def main(_):
# Environment
env_name = "Breakout-v4"
train_num_parallel_environments = 5
max_steps_per_episode = 1000
# Replay buffer
replay_buffer_capacity = 50000
init_replay_buffer = 500
# Driver
collect_steps_per_iteration = 1 * train_num_parallel_environments
# Training
train_batch_size = 32
train_iterations = 100000
train_summary_interval = 200
train_checkpoint_interval = 200
# Evaluation
eval_num_parallel_environments = 5
eval_summary_interval = 500
eval_num_episodes = 20
# File paths
path = pathlib.Path(__file__)
parent_dir = path.parent.resolve()
folder_name = path.stem + time.strftime("_%Y%m%d_%H%M%S")
train_checkpoint_dir = str(parent_dir / folder_name / "train_checkpoint")
train_summary_dir = str(parent_dir / folder_name / "train_summary")
eval_summary_dir = str(parent_dir / folder_name / "eval_summary")
# Parallel training environment
tf_env = TFPyEnvironment(
ParallelPyEnvironment([
lambda: suite_atari.load(
env_name,
env_wrappers=
[lambda env: TimeLimit(env, duration=max_steps_per_episode)],
gym_env_wrappers=[AtariPreprocessing, FrameStack4],
)
] * train_num_parallel_environments))
tf_env.seed([42] * tf_env.batch_size)
tf_env.reset()
# Parallel evaluation environment
eval_tf_env = TFPyEnvironment(
ParallelPyEnvironment([
lambda: suite_atari.load(
env_name,
env_wrappers=
[lambda env: TimeLimit(env, duration=max_steps_per_episode)],
gym_env_wrappers=[AtariPreprocessing, FrameStack4],
)
] * eval_num_parallel_environments))
eval_tf_env.seed([42] * eval_tf_env.batch_size)
eval_tf_env.reset()
# Creating the Deep Q-Network
preprocessing_layer = keras.layers.Lambda(
lambda obs: tf.cast(obs, np.float32) / 255.)
conv_layer_params = [(32, (8, 8), 4), (64, (4, 4), 2), (64, (3, 3), 1)]
fc_layer_params = [512]
q_net = QNetwork(tf_env.observation_spec(),
tf_env.action_spec(),
preprocessing_layers=preprocessing_layer,
conv_layer_params=conv_layer_params,
fc_layer_params=fc_layer_params)
# Creating the DQN Agent
optimizer = keras.optimizers.RMSprop(lr=2.5e-4,
rho=0.95,
momentum=0.0,
epsilon=0.00001,
centered=True)
epsilon_fn = keras.optimizers.schedules.PolynomialDecay(
initial_learning_rate=1.0, # initial ε
decay_steps=2500000,
end_learning_rate=0.01) # final ε
global_step = tf.compat.v1.train.get_or_create_global_step()
agent = DqnAgent(
tf_env.time_step_spec(),
tf_env.action_spec(),
q_network=q_net,
optimizer=optimizer,
target_update_period=200,
td_errors_loss_fn=keras.losses.Huber(reduction="none"),
gamma=0.99, # discount factor
train_step_counter=global_step,
epsilon_greedy=lambda: epsilon_fn(global_step))
agent.initialize()
# Creating the Replay Buffer
replay_buffer = tf_uniform_replay_buffer.TFUniformReplayBuffer(
data_spec=agent.collect_data_spec,
batch_size=tf_env.batch_size,
max_length=replay_buffer_capacity)
# Observer: Replay Buffer Observer
replay_buffer_observer = replay_buffer.add_batch
# Observer: Training Metrics
train_metrics = [
tf_metrics.NumberOfEpisodes(),
tf_metrics.EnvironmentSteps(),
tf_metrics.AverageReturnMetric(batch_size=tf_env.batch_size),
tf_metrics.AverageEpisodeLengthMetric(batch_size=tf_env.batch_size),
]
# Creating the Collect Driver
collect_driver = DynamicStepDriver(tf_env,
agent.collect_policy,
observers=[replay_buffer_observer] +
train_metrics,
num_steps=collect_steps_per_iteration)
# Initialize replay buffer
initial_collect_policy = RandomTFPolicy(tf_env.time_step_spec(),
tf_env.action_spec())
init_driver = DynamicStepDriver(
tf_env,
initial_collect_policy,
observers=[replay_buffer_observer,
ShowProgress()],
num_steps=init_replay_buffer)
final_time_step, final_policy_state = init_driver.run()
# Creating the Dataset
dataset = replay_buffer.as_dataset(sample_batch_size=train_batch_size,
num_steps=2,
num_parallel_calls=3).prefetch(3)
# Optimize by wrapping some of the code in a graph using TF function.
collect_driver.run = function(collect_driver.run)
agent.train = function(agent.train)
print("\n\n++++++++++++++++++++++++++++++++++\n")
# Create checkpoint
train_checkpointer = Checkpointer(
ckpt_dir=train_checkpoint_dir,
max_to_keep=1,
agent=agent,
# replay_buffer=replay_buffer,
global_step=global_step,
# metrics=metric_utils.MetricsGroup(train_metrics, 'train_metrics')
)
# Restore checkpoint
# train_checkpointer.initialize_or_restore()
# Summary writers and metrics
train_summary_writer = tf.summary.create_file_writer(train_summary_dir)
eval_summary_writer = tf.summary.create_file_writer(eval_summary_dir)
eval_metrics = [
tf_metrics.NumberOfEpisodes(),
tf_metrics.EnvironmentSteps(),
tf_metrics.AverageReturnMetric(batch_size=eval_tf_env.batch_size,
buffer_size=eval_num_episodes),
tf_metrics.AverageEpisodeLengthMetric(
batch_size=eval_tf_env.batch_size, buffer_size=eval_num_episodes)
]
# Create evaluate callback function
eval_callback = evaluate(eval_metrics=eval_metrics,
eval_tf_env=eval_tf_env,
eval_policy=agent.policy,
eval_num_episodes=eval_num_episodes,
train_step=global_step,
eval_summary_writer=eval_summary_writer)
# Train agent
train_agent(tf_env=tf_env,
train_iterations=train_iterations,
global_step=global_step,
agent=agent,
dataset=dataset,
collect_driver=collect_driver,
train_metrics=train_metrics,
train_checkpointer=train_checkpointer,
train_checkpoint_interval=train_checkpoint_interval,
train_summary_writer=train_summary_writer,
train_summary_interval=train_summary_interval,
eval_summary_interval=eval_summary_interval,
eval_callback=eval_callback)
print("\n\n++++++++++ END OF TF_AGENTS RL TRAINING ++++++++++\n\n")
update_period = 4 # run a training step every 4 collect steps
optimizer = tf.compat.v1.train.RMSPropOptimizer(learning_rate=2.5e-4,
decay=0.95,
momentum=0.0,
epsilon=0.00001,
centered=True)
epsilon_fn = tf.keras.optimizers.schedules.PolynomialDecay(
initial_learning_rate=1.0, # initial ε
decay_steps=250000 // update_period, # <=> 1,000,000 ALE frames
end_learning_rate=0.01) # final ε
agent = DqnAgent(
tf_env.time_step_spec(),
tf_env.action_spec(),
q_network=q_net,
optimizer=optimizer,
target_update_period=2000, # <=> 32,000 ALE frames
td_errors_loss_fn=tf.keras.losses.Huber(reduction="none"),
gamma=0.99, # discount factor
train_step_counter=train_step,
epsilon_greedy=lambda: epsilon_fn(train_step))
agent.initialize()
replay_buffer = tf_uniform_replay_buffer.TFUniformReplayBuffer(
data_spec=agent.collect_data_spec,
batch_size=tf_env.batch_size,
max_length=1000000)
replay_buffer_observer = replay_buffer.add_batch
def breakout_v4(seed=42):
env = suite_gym.load("Breakout-v4")
env.seed(seed)
env.reset()
repeating_env = ActionRepeat(env, times=4)
for name in dir(tf_agents.environments.wrappers):
obj = getattr(tf_agents.environments.wrappers, name)
if hasattr(obj, "__base__") and issubclass(
obj, tf_agents.environments.wrappers.PyEnvironmentBaseWrapper):
print("{:27s} {}".format(name, obj.__doc__.split("\n")[0]))
limited_repeating_env = suite_gym.load(
"Breakout-v4",
gym_env_wrappers=[partial(TimeLimit, max_episode_steps=10000)],
env_wrappers=[partial(ActionRepeat, times=4)],
)
max_episode_steps = 27000 # <=> 108k ALE frames since 1 step = 4 frames
environment_name = "BreakoutNoFrameskip-v4"
env = suite_atari.load(
environment_name,
max_episode_steps=max_episode_steps,
gym_env_wrappers=[AtariPreprocessing, FrameStack4],
)
env.seed(42)
env.reset()
time_step = env.step(np.array(1)) # FIRE
for _ in range(4):
time_step = env.step(np.array(3)) # LEFT
def plot_observation(obs):
# Since there are only 3 color channels, you cannot display 4 frames
# with one primary color per frame. So this code computes the delta between
# the current frame and the mean of the other frames, and it adds this delta
# to the red and blue channels to get a pink color for the current frame.
obs = obs.astype(np.float32)
img_ = obs[..., :3]
current_frame_delta = np.maximum(
obs[..., 3] - obs[..., :3].mean(axis=-1), 0.0)
img_[..., 0] += current_frame_delta
img_[..., 2] += current_frame_delta
img_ = np.clip(img_ / 150, 0, 1)
plt.imshow(img_)
plt.axis("off")
plt.figure(figsize=(6, 6))
plot_observation(time_step.observation)
plt.tight_layout()
plt.savefig("./images/preprocessed_breakout_plot.png",
format="png",
dpi=300)
plt.show()
tf_env = TFPyEnvironment(env)
preprocessing_layer = keras.layers.Lambda(
lambda obs: tf.cast(obs, np.float32) / 255.0)
conv_layer_params = [(32, (8, 8), 4), (64, (4, 4), 2), (64, (3, 3), 1)]
fc_layer_params = [512]
q_net = QNetwork(
tf_env.observation_spec(),
tf_env.action_spec(),
preprocessing_layers=preprocessing_layer,
conv_layer_params=conv_layer_params,
fc_layer_params=fc_layer_params,
)
# see TF-agents issue #113
# optimizer = keras.optimizers.RMSprop(lr=2.5e-4, rho=0.95, momentum=0.0,
# epsilon=0.00001, centered=True)
train_step = tf.Variable(0)
update_period = 4 # run a training step every 4 collect steps
optimizer = tf.compat.v1.train.RMSPropOptimizer(learning_rate=2.5e-4,
decay=0.95,
momentum=0.0,
epsilon=0.00001,
centered=True)
epsilon_fn = keras.optimizers.schedules.PolynomialDecay(
initial_learning_rate=1.0, # initial ε
decay_steps=250000 // update_period, # <=> 1,000,000 ALE frames
end_learning_rate=0.01,
) # final ε
agent = DqnAgent(
tf_env.time_step_spec(),
tf_env.action_spec(),
q_network=q_net,
optimizer=optimizer,
target_update_period=2000, # <=> 32,000 ALE frames
td_errors_loss_fn=keras.losses.Huber(reduction="none"),
gamma=0.99, # discount factor
train_step_counter=train_step,
epsilon_greedy=lambda: epsilon_fn(train_step),
)
agent.initialize()
from tf_agents.replay_buffers import tf_uniform_replay_buffer
replay_buffer = tf_uniform_replay_buffer.TFUniformReplayBuffer(
data_spec=agent.collect_data_spec,
batch_size=tf_env.batch_size,
max_length=1000000)
replay_buffer_observer = replay_buffer.add_batch
class ShowProgress:
def __init__(self, total):
self.counter = 0
self.total = total
def __call__(self, trajectory):
if not trajectory.is_boundary():
self.counter += 1
if self.counter % 100 == 0:
print("\r{}/{}".format(self.counter, self.total), end="")
from tf_agents.metrics import tf_metrics
train_metrics = [
tf_metrics.NumberOfEpisodes(),
tf_metrics.EnvironmentSteps(),
tf_metrics.AverageReturnMetric(),
tf_metrics.AverageEpisodeLengthMetric(),
]
from tf_agents.eval.metric_utils import log_metrics
import logging
logging.getLogger().setLevel(logging.INFO)
log_metrics(train_metrics)
from tf_agents.drivers.dynamic_step_driver import DynamicStepDriver
collect_driver = DynamicStepDriver(
tf_env,
agent.collect_policy,
observers=[replay_buffer_observer] + train_metrics,
num_steps=update_period,
) # collect 4 steps for each training iteration
from tf_agents.policies.random_tf_policy import RandomTFPolicy
initial_collect_policy = RandomTFPolicy(tf_env.time_step_spec(),
tf_env.action_spec())
init_driver = DynamicStepDriver(
tf_env,
initial_collect_policy,
observers=[replay_buffer.add_batch,
ShowProgress(20000)],
num_steps=20000,
) # <=> 80,000 ALE frames
final_time_step, final_policy_state = init_driver.run()
train_env = TFPyEnvironment(parallel_env)
# train_env = TFPyEnvironment(suite_gym.load(env_name))
eval_env = TFPyEnvironment(suite_gym.load(env_name))
fc_layer_params = (100,)
q_net = QNetwork(
train_env.observation_spec(),
train_env.action_spec(),
fc_layer_params=fc_layer_params
)
train_step_counter = tf.Variable(0)
agent = DqnAgent(
train_env.time_step_spec(),
train_env.action_spec(),
q_network=q_net,
optimizer=Adam(learning_rate=LEARNING_RATE),
td_errors_loss_fn=common.element_wise_squared_loss,
train_step_counter=train_step_counter
)
agent.initialize()
random_policy = RandomTFPolicy(
train_env.time_step_spec(),
train_env.action_spec()
)
def compute_avg_return(environment, policy, num_episodes=10):
total_return = 0
for _ in range(num_episodes):
time_step = environment.reset()
episode_return = 0
hidden_layers = (100, )
dqn_network = QNetwork(train_env.observation_spec(),
train_env.action_spec(),
fc_layer_params=hidden_layers)
ddqn_network = QNetwork(train_env.observation_spec(),
train_env.action_spec(),
fc_layer_params=hidden_layers)
counter = tf.Variable(0)
dqn_agent = DqnAgent(
train_env.time_step_spec(),
train_env.action_spec(),
q_network=dqn_network,
optimizer=tf.compat.v1.train.AdamOptimizer(learning_rate=1e-3),
td_errors_loss_fn=common.element_wise_squared_loss,
train_step_counter=counter)
ddqn_agent = DdqnAgent(
train_env.time_step_spec(),
train_env.action_spec(),
q_network=ddqn_network,
optimizer=tf.compat.v1.train.AdamOptimizer(learning_rate=1e-3),
td_errors_loss_fn=common.element_wise_squared_loss,
train_step_counter=counter)
dqn_agent.initialize()
ddqn_agent.initialize()