tf_agents.agents.tf_agent.TFAgent

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Abstract base class for TF RL agents.

time_step_spec A nest of tf.TypeSpec representing the time_steps. Provided by the user.
action_spec A nest of BoundedTensorSpec representing the actions. Provided by the user.
policy An instance of tf_policy.Base representing the Agent's current policy.
collect_policy An instance of tf_policy.Base representing the Agent's current data collection policy (used to set self.step_spec).
train_sequence_length A python integer or None, signifying the number of time steps required from tensors in experience as passed to train(). All tensors in experience will be shaped [B, T, ...] but for certain agents, T should be fixed. For example, DQN requires transitions in the form of 2 time steps, so for a non-RNN DQN Agent, set this value to 2. For agents that don't care, or which can handle T unknown at graph build time (i.e. most RNN-based agents), set this argument to None.
num_outer_dims The number of outer dimensions for the agent. Must be either 1 or 2. If 2, training will require both a batch_size and time dimension on every Tensor; if 1, training will require only a batch_size outer dimension.
train_argspec (Optional) Describes additional supported arguments to the train call. This must be a dict mapping strings to nests of specs. Overriding the experience arg is also supported.

Some algorithms require additional arguments to the train() call, and while TF-Agents encourages most of these to be provided in the policy_info / info field of experience, sometimes the extra information doesn't fit well, i.e., when it doesn't come from the policy.

Below is an example:

class MyAgent(TFAgent):
def __init__(self, counterfactual_training, ...):
collect_policy = ...
train_argspec = None
if counterfactual_training:
train_argspec = dict(
counterfactual=collect_policy.trajectory_spec)
super(...).__init__(
...
train_argspec=train_argspec)

my_agent = MyAgent(...)

for ...:
experience, counterfactual = next(experience_and_counterfactual_iter)
loss_info = my_agent.train(experience, counterfactual=counterfactual)

debug_summaries A bool; if true, subclasses should gather debug summaries.
summarize_grads_and_vars A bool; if true, subclasses should additionally collect gradient and variable summaries.
enable_summaries A bool; if false, subclasses should not gather any summaries (debug or otherwise); subclasses should gate all summaries using either summaries_enabled, debug_summaries, or summarize_grads_and_vars properties.
train_step_counter An optional counter to increment every time the train op is run. Defaults to the global_step.

TypeError If train_argspec is not a dict.
ValueError If train_argspec has the keys experience or weights.
TypeError If any leaf nodes in train_argspec values are not subclasses of tf.TypeSpec.
ValueError If time_step_spec is not an instance of ts.TimeStep.
ValueError If num_outer_dims is not in [1, 2].

action_spec TensorSpec describing the action produced by the agent.
collect_data_spec Returns a Trajectory spec, as expected by the collect_policy.
collect_policy Return a policy that can be used to collect data from the environment.
debug_summaries

name Returns the name of this module as passed or determined in the ctor.

name_scope Returns a tf.name_scope instance for this class.
policy Return the current policy held by the agent.
submodules Sequence of all sub-modules.

Submodules are modules which are properties of this module, or found as properties of modules which are properties of this module (and so on).

a = tf.Module()
b = tf.Module()
c = tf.Module()
a.b = b
b.c = c
list(a.submodules) == [b, c]
True
list(b.submodules) == [c]
True
list(c.submodules) == []
True

summaries_enabled

summarize_grads_and_vars

time_step_spec Describes the TimeStep tensors expected by the agent.
train_argspec TensorSpec describing extra supported kwargs to train().
train_sequence_length The number of time steps needed in experience tensors passed to train.

Train requires experience to be a Trajectory containing tensors shaped [B, T, ...]. This argument describes the value of T required.

For example, for non-RNN DQN training, T=2 because DQN requires single transitions.

If this value is None, then train can handle an unknown T (it can be determined at runtime from the data). Most RNN-based agents fall into this category.

train_step_counter

trainable_variables Sequence of trainable variables owned by this module and its submodules.

variables Sequence of variables owned by this module and its submodules.

Methods

initialize

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Initializes the agent.

Returns
An operation that can be used to initialize the agent.

Raises
RuntimeError If the class was not initialized properly (super.__init__ was not called).

train

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Trains the agent.

Args
experience A batch of experience data in the form of a Trajectory. The structure of experience must match that of self.collect_data_spec. All tensors in experience must be shaped [batch, time, ...] where time must be equal to self.train_step_length if that property is not None.
weights (optional). A Tensor, either 0-D or shaped [batch], containing weights to be used when calculating the total train loss. Weights are typically multiplied elementwise against the per-batch loss, but the implementation is up to the Agent.
**kwargs Any additional data as declared by self.train_argspec.

Returns
A LossInfo loss tuple containing loss and info tensors.

  • In eager mode, the loss values are first calculated, then a train step is performed before they are returned.
  • In graph mode, executing any or all of the loss tensors will first calculate the loss value(s), then perform a train step, and return the pre-train-step LossInfo.

Raises
TypeError If experience is not type Trajectory. Or if experience does not match self.collect_data_spec structure types.
ValueError If experience tensors' time axes are not compatible with self.train_sequence_length. Or if experience does not match self.collect_data_spec structure.
ValueError If the user does not pass **kwargs matching self.train_argspec.
RuntimeError If the class was not initialized properly (super.__init__ was not called).

with_name_scope

Decorator to automatically enter the module name scope.

class MyModule(tf.Module):
  @tf.Module.with_name_scope
  def __call__(self, x):
    if not hasattr(self, 'w'):
      self.w = tf.Variable(tf.random.normal([x.shape[1], 3]))
    return tf.matmul(x, self.w)

Using the above module would produce tf.Variables and tf.Tensors whose names included the module name:

mod = MyModule()
mod(tf.ones([1, 2]))
<tf.Tensor: shape=(1, 3), dtype=float32, numpy=..., dtype=float32)>
mod.w
<tf.Variable 'my_module/Variable:0' shape=(2, 3) dtype=float32,
numpy=..., dtype=float32)>

Args
method The method to wrap.

Returns
The original method wrapped such that it enters the module's name scope.