def fit(self,
env,
nb_steps,
action_repetition=1,
callbacks=None,
verbose=1,
visualize=False,
nb_max_start_steps=0,
start_step_policy=None,
log_interval=10000,
nb_max_episode_steps=None,
reset_episode_logger=True):
"""Trains the agent on the given environment.
# Arguments
env: (`Env` instance): Environment that the agent interacts with. See [Env](#env) for details.
nb_steps (integer): Number of training steps to be performed.
action_repetition (integer): Number of times the agent repeats the same action without
observing the environment again. Setting this to a value > 1 can be useful
if a single action only has a very small effect on the environment.
callbacks (list of `keras.callbacks.Callback` or `rl.callbacks.Callback` instances):
List of callbacks to apply during training. See [callbacks](/callbacks) for details.
verbose (integer): 0 for no logging, 1 for interval logging (compare `log_interval`), 2 for episode logging
visualize (boolean): If `True`, the environment is visualized during training. However,
this is likely going to slow down training significantly and is thus intended to be
a debugging instrument.
nb_max_start_steps (integer): Number of maximum steps that the agent performs at the beginning
of each episode using `start_step_policy`. Notice that this is an upper limit since
the exact number of steps to be performed is sampled uniformly from [0, max_start_steps]
at the beginning of each episode.
start_step_policy (`lambda observation: action`): The policy
to follow if `nb_max_start_steps` > 0. If set to `None`, a random action is performed.
log_interval (integer): If `verbose` = 1, the number of steps that are considered to be an interval.
nb_max_episode_steps (integer): Number of steps per episode that the agent performs before
automatically resetting the environment. Set to `None` if each episode should run
(potentially indefinitely) until the environment signals a terminal state.
reset_episode_logger(bool): Determines whether the episode logger retains data from previous episodes.
# Returns
A `keras.callbacks.History` instance that recorded the entire training process.
"""
if not self.compiled:
raise RuntimeError(
'Your tried to fit your agent but it hasn\'t been compiled yet. Please call `compile()` before `fit()`.'
)
if action_repetition < 1:
raise ValueError('action_repetition must be >= 1, is {}'.format(
action_repetition))
self.training = True
callbacks = [] if not callbacks else callbacks[:]
if verbose == 1:
callbacks += [TrainIntervalLogger(interval=log_interval)]
elif verbose > 1:
callbacks += [TrainEpisodeLogger()]
if visualize:
callbacks += [Visualizer()]
history = History()
callbacks += [history]
callbacks = CallbackList(callbacks)
if hasattr(callbacks, 'set_model'):
callbacks.set_model(self)
else:
callbacks._set_model(self)
#import ipdb; ipdb.set_trace() # debugging starts here
callbacks._set_reset_episode_logger(reset_episode_logger)
callbacks._set_env(env)
params = {
'nb_steps': nb_steps,
}
if hasattr(callbacks, 'set_params'):
callbacks.set_params(params)
else:
callbacks._set_params(params)
self._on_train_begin()
callbacks.on_train_begin()
episode = np.int16(0)
self.step = np.int16(0)
observation = None
episode_reward = None
episode_step = None
did_abort = False
try:
while self.step < nb_steps:
if observation is None: # start of a new episode
callbacks.on_episode_begin(episode)
episode_step = np.int16(0)
episode_reward = np.float32(0)
# Obtain the initial observation by resetting the environment.
self.reset_states()
observation = deepcopy(env.reset())
if self.processor is not None:
observation = self.processor.process_observation(
observation)
assert observation is not None
# Perform random starts at beginning of episode and do not record them into the experience.
# This slightly changes the start position between games.
nb_random_start_steps = 0 if nb_max_start_steps == 0 else np.random.randint(
nb_max_start_steps)
for _ in range(nb_random_start_steps):
if start_step_policy is None:
action = env.action_space.sample()
else:
action = start_step_policy(observation)
if self.processor is not None:
action = self.processor.process_action(action)
callbacks.on_action_begin(action)
observation, reward, done, info = env.step(action)
observation = deepcopy(observation)
if self.processor is not None:
observation, reward, done, info = self.processor.process_step(
observation, reward, done, info)
callbacks.on_action_end(action)
if done:
warnings.warn(
'Env ended before {} random steps could be performed at the start. You should probably lower the `nb_max_start_steps` parameter.'
.format(nb_random_start_steps))
observation = deepcopy(env.reset())
if self.processor is not None:
observation = self.processor.process_observation(
observation)
break
# At this point, we expect to be fully initialized.
assert episode_reward is not None
assert episode_step is not None
assert observation is not None
# Run a single step.
callbacks.on_step_begin(episode_step)
# This is were all of the work happens. We first perceive and compute the action
# (forward step) and then use the reward to improve (backward step).
action = self.forward(observation)
if self.processor is not None:
action = self.processor.process_action(action)
reward = np.float32(0)
accumulated_info = {}
done = False
for _ in range(action_repetition):
callbacks.on_action_begin(action)
observation, r, done, info = env.step(action)
observation = deepcopy(observation)
if self.processor is not None:
observation, r, done, info = self.processor.process_step(
observation, r, done, info)
for key, value in info.items():
if not np.isreal(value):
continue
if key not in accumulated_info:
accumulated_info[key] = np.zeros_like(value)
accumulated_info[key] += value
callbacks.on_action_end(action)
reward += r
if done:
break
if nb_max_episode_steps and episode_step >= nb_max_episode_steps - 1:
# Force a terminal state.
done = True
metrics = self.backward(reward, terminal=done)
episode_reward += reward
step_logs = {
'action': action,
'observation': observation,
'reward': reward,
'metrics': metrics,
'episode': episode,
'info': accumulated_info,
}
callbacks.on_step_end(episode_step, step_logs)
episode_step += 1
self.step += 1
if done:
# We are in a terminal state but the agent hasn't yet seen it. We therefore
# perform one more forward-backward call and simply ignore the action before
# resetting the environment. We need to pass in `terminal=False` here since
# the *next* state, that is the state of the newly reset environment, is
# always non-terminal by convention.
self.forward(observation)
self.backward(0., terminal=False)
# This episode is finished, report and reset.
episode_logs = {
'episode_reward': episode_reward,
'nb_episode_steps': episode_step,
'nb_steps': self.step,
}
callbacks.on_episode_end(episode, episode_logs)
episode += 1
observation = None
episode_step = None
episode_reward = None
except KeyboardInterrupt:
# We catch keyboard interrupts here so that training can be be safely aborted.
# This is so common that we've built this right into this function, which ensures that
# the `on_train_end` method is properly called.
did_abort = True
callbacks.on_train_end(logs={'did_abort': did_abort})
self._on_train_end()
return callbacks
