tf_agents.environments.random_py_environment.RandomPyEnvironment

Randomly generates observations following the given observation_spec.

Inherits From: PyEnvironment

Used in the notebooks

Used in the tutorials

If an action_spec is provided it validates that the actions used to step the environment fall within the defined spec.

observation_spec An ArraySpec, or a nested dict, list or tuple of ArraySpecs.
action_spec An ArraySpec, or a nested dict, list or tuple of ArraySpecs.
episode_end_probability Probability an episode will end when the environment is stepped.
discount Discount to set in time_steps.
reward_fn Callable that takes in step_type, action, an observation(s), and returns a numpy array of rewards.
batch_size (Optional) Number of observations generated per call. If this value is not None, then all actions are expected to have an additional major axis of size batch_size, and all outputs will have an additional major axis of size batch_size.
seed Seed to use for rng used in observation generation.
render_size Size of the random render image to return when calling render.
min_duration Number of steps at the beginning of the episode during which the episode can not terminate.
max_duration Optional number of steps after which the episode terminates regarless of the termination probability.

ValueError If batch_size argument is not None and does not match the shapes of discount or reward.

batch_size The batch size of the environment.
batched Whether the environment is batched or not.

If the environment supports batched observations and actions, then overwrite this property to True.

A batched environment takes in a batched set of actions and returns a batched set of observations. This means for all numpy arrays in the input and output nested structures, the first dimension is the batch size.

When batched, the left-most dimension is not part of the action_spec or the observation_spec and corresponds to the batch dimension.

Methods

action_spec

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Defines the actions that should be provided to step().

May use a subclass of ArraySpec that specifies additional properties such as min and max bounds on the values.

Returns
An ArraySpec, or a nested dict, list or tuple of ArraySpecs.

close

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Frees any resources used by the environment.

Implement this method for an environment backed by an external process.

This method be used directly

env = Env(...)
# Use env.
env.close()

or via a context manager

with Env(...) as env:
  # Use env.

current_time_step

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Returns the current timestep.

discount_spec

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Defines the discount that are returned by step().

Override this method to define an environment that uses non-standard discount values, for example an environment with array-valued discounts.

Returns
An ArraySpec, or a nested dict, list or tuple of ArraySpecs.

get_info

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Returns the environment info returned on the last step.

Returns
Info returned by last call to step(). None by default.

Raises
NotImplementedError If the environment does not use info.

get_state

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Returns the state of the environment.

The state contains everything required to restore the environment to the current configuration. This can contain e.g.

  • The current time_step.
  • The number of steps taken in the environment (for finite horizon MDPs).
  • Hidden state (for POMDPs).

Callers should not assume anything about the contents or format of the returned state. It should be treated as a token that can be passed back to set_state() later.

Note that the returned state handle should not be modified by the environment later on, and ensuring this (e.g. using copy.deepcopy) is the responsibility of the environment.

Returns
state The current state of the environment.

observation_spec

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Defines the observations provided by the environment.

May use a subclass of ArraySpec that specifies additional properties such as min and max bounds on the values.

Returns
An ArraySpec, or a nested dict, list or tuple of ArraySpecs.

render

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Renders the environment.

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

Returns
An ndarray 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

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Starts a new sequence and returns the first TimeStep of this sequence.

Returns
A TimeStep namedtuple containing: step_type: A StepType of FIRST. reward: 0.0, indicating the reward. discount: 1.0, indicating the discount. observation: A NumPy array, or a nested dict, list or tuple of arrays corresponding to observation_spec().

reward_spec

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Defines the rewards that are returned by step().

Override this method to define an environment that uses non-standard reward values, for example an environment with array-valued rewards.

Returns
An ArraySpec, or a nested dict, list or tuple of ArraySpecs.

seed

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Seeds the environment.

Args
seed Value to use as seed for the environment.

set_state

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Restores the environment to a given state.

See definition of state in the documentation for get_state().

Args
state A state to restore the environment to.

step

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Updates the environment according to the action and returns a TimeStep.

If the environment returned a TimeStep with StepType.LAST at the previous step the implementation of _step in the environment should call reset to start a new sequence and ignore action.

This method will 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.

Args
action A NumPy array, or a nested dict, list or tuple of arrays corresponding to action_spec().

Returns
A TimeStep namedtuple containing: step_type: A StepType value. reward: A NumPy array, reward value for this timestep. discount: A NumPy array, discount in the range [0, 1]. observation: A NumPy array, or a nested dict, list or tuple of arrays corresponding to observation_spec().

time_step_spec

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Describes the TimeStep fields returned by step().

Override this method to define an environment that uses non-standard values for any of the items returned by step(). For example, an environment with array-valued rewards.

Returns
A TimeStep namedtuple containing (possibly nested) ArraySpecs defining the step_type, reward, discount, and observation structure.

__enter__

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Allows the environment to be used in a with-statement context.

__exit__

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Allows the environment to be used in a with-statement context.