tf_agents.environments.tf_py_environment.TFPyEnvironment

Exposes a Python environment as an in-graph TF environment.

Inherits From: TFEnvironment

Used in the notebooks

Used in the tutorials

This class supports Python environments that return nests of arrays as observations and accept nests of arrays as actions. The nest structure is reflected in the in-graph environment's observation and action structure.

Implementation notes:

  • Since tf.py_func deals in lists of tensors, this class has some additional tf.nest.flatten and tf.nest.pack_structure_as calls.

  • This class currently cast rewards and discount to float32.

environment Environment to interact with, implementing py_environment.PyEnvironment. Or a callable that returns an environment of this form. If a callable is provided and thread_isolation is provided, the callable is executed in the dedicated thread.
check_dims Whether should check batch dimensions of actions in step.
isolation If this value is False (default), interactions with the environment will occur within whatever thread the methods of the TFPyEnvironment are run from. For example, in TF graph mode, methods like step are called from multiple threads created by the TensorFlow engine; calls to step the environment are guaranteed to be sequential, but not from the same thread. This creates problems for environments that are not thread-safe.

Using isolation ensures not only that a dedicated thread (or thread-pool) is used to interact with the environment, but also that interaction with the environment happens in a serialized manner.

If isolation == True, a dedicated thread is created for interactions with the environment.

If isolation is an instance of multiprocessing.pool.Pool (this includes instances of multiprocessing.pool.ThreadPool, nee multiprocessing.dummy.Pool and multiprocessing.Pool, then this pool is used to interact with the environment.

TypeError If environment is not an instance of py_environment.PyEnvironment or subclasses, or is a callable that does not return an instance of PyEnvironment.
TypeError If isolation is not True, False, or an instance of multiprocessing.pool.Pool.

batch_size

batched

pyenv Returns the underlying Python environment.

Methods

action_spec

View source

Describes the specs of the Tensors expected by step(action).

action can be a single Tensor, or a nested dict, list or tuple of Tensors.

Returns
An single TensorSpec, or a nested dict, list or tuple of TensorSpec objects, which describe the shape and dtype of each Tensor expected by step().

close

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Send close to wrapped env & also to the isolation pool + join it.

Only closes pool when isolation was provided at init time.

current_time_step

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Returns the current TimeStep.

Returns
A TimeStep namedtuple containing: step_type: A StepType value. reward: Reward at this time_step. discount: A discount in the range [0, 1]. observation: A Tensor, or a nested dict, list or tuple of Tensors corresponding to observation_spec().

observation_spec

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Defines the TensorSpec of observations provided by the environment.

Returns
A TensorSpec, or a nested dict, list or tuple of TensorSpec objects, which describe the observation.

render

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Renders the environment.

Note for compatibility this will convert the image to uint8.

Args
mode One of ['rgb_array', 'human']. Renders to an numpy array, or brings up a window where the environment can be visualized.

Returns
A Tensor of shape [width, height, 3] denoting an RGB image if mode is rgb_array. Otherwise return nothing and render directly to a display window.

Raises
NotImplementedError If the environment does not support rendering.

reset

View source

Resets the environment and returns the current time_step.

Returns
A TimeStep namedtuple containing: step_type: A StepType value. reward: Reward at this time_step. discount: A discount in the range [0, 1]. observation: A Tensor, or a nested dict, list or tuple of Tensors corresponding to observation_spec().

reward_spec

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Defines the TensorSpec of rewards provided by the environment.

Returns
A TensorSpec, or a nested dict, list or tuple of TensorSpec objects, which describe the observation.

step

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Steps the environment according to the action.

If the environment returned a TimeStep with StepType.LAST at the previous step, this call to step should reset the environment (note that it is expected that whoever defines this method, calls reset in this case), start a new sequence and action will be ignored.

This method will also start a new sequence if called after the environment has been constructed and reset() has not been called. In this case action will be ignored.

Expected sequences look like:

time_step -> action -> next_time_step

The action should depend on the previous time_step for correctness.

Args
action A Tensor, or a nested dict, list or tuple of Tensors corresponding to action_spec().

Returns
A TimeStep namedtuple containing: step_type: A StepType value. reward: Reward at this time_step. discount: A discount in the range [0, 1]. observation: A Tensor, or a nested dict, list or tuple of Tensors corresponding to observation_spec().

time_step_spec

View source

Describes the TimeStep specs of Tensors returned by step().

Returns
A TimeStep namedtuple containing TensorSpec objects defining the Tensors returned by step(), i.e. (step_type, reward, discount, observation).