ParallelEnv

class torchrl.envs.ParallelEnv(*args, **kwargs)

Creates one environment per process.

TensorDicts are passed via shared memory or memory map.

Batched environments allow the user to query an arbitrary method / attribute of the environment running remotely.

Those queries will return a list of length equal to the number of workers containing the values resulting from those queries.

>>> env = ParallelEnv(3, my_env_fun)
>>> custom_attribute_list = env.custom_attribute
>>> custom_method_list = env.custom_method(*args)

Parameters:

• num_workers – number of workers (i.e. env instances) to be deployed simultaneously;

• create_env_fn (callable or list of callables) – function (or list of functions) to be used for the environment creation. If a single task is used, a callable should be used and not a list of identical callables: if a list of callable is provided, the environment will be executed as if multiple, diverse tasks were needed, which comes with a slight compute overhead;

Keyword Arguments:

• create_env_kwargs (dict or list of dicts, optional) – kwargs to be used with the environments being created;

• share_individual_td (bool, optional) – if True, a different tensordict is created for every process/worker and a lazy stack is returned. default = None (False if single task);

• shared_memory (bool) – whether the returned tensordict will be placed in shared memory;

• memmap (bool) – whether the returned tensordict will be placed in memory map.

• policy_proof (callable, optional) – if provided, it’ll be used to get the list of tensors to return through the step() and reset() methods, such as "hidden" etc.

• device (str, int, torch.device) – The device of the batched environment can be passed. If not, it is inferred from the env. In this case, it is assumed that the device of all environments match. If it is provided, it can differ from the sub-environment device(s). In that case, the data will be automatically cast to the appropriate device during collection. This can be used to speed up collection in case casting to device introduces an overhead (eg, numpy-based environents etc.): by using a "cuda" device for the batched environment but a "cpu" device for the nested environments, one can keep the overhead to a minimum.

• num_threads (int, optional) – number of threads for this process. Should be equal to one plus the number of processes launched within each subprocess (or one if a single process is launched). Defaults to the number of workers + 1. This parameter has no effect for the SerialEnv class.

• num_sub_threads (int, optional) – number of threads of the subprocesses. Defaults to 1 for safety: if none is indicated, launching multiple workers may charge the cpu load too much and harm performance. This parameter has no effect for the SerialEnv class.

• serial_for_single (bool, optional) – if True, creating a parallel environment with a single worker will return a SerialEnv instead. This option has no effect with SerialEnv. Defaults to False.

• non_blocking (bool, optional) – if True, device moves will be done using the non_blocking=True option. Defaults to True.

• mp_start_method (str, optional) – the multiprocessing start method. Uses the default start method if not indicated (‘spawn’ by default in TorchRL if not initiated differently before first import). To be used only with ParallelEnv subclasses.

• use_buffers (bool, optional) –

  whether communication between workers should occur via circular preallocated memory buffers. Defaults to True unless one of the environment has dynamic specs.

  Note

  Learn more about dynamic specs and environments here.

Note

One can pass keyword arguments to each sub-environments using the following technique: every keyword argument in reset() will be passed to each environment except for the list_of_kwargs argument which, if present, should contain a list of the same length as the number of workers with the worker-specific keyword arguments stored in a dictionary. If a partial reset is queried, the element of list_of_kwargs corresponding to sub-environments that are not reset will be ignored.

Examples

>>> from torchrl.envs import GymEnv, ParallelEnv, SerialEnv, EnvCreator
>>> make_env = EnvCreator(lambda: GymEnv("Pendulum-v1")) # EnvCreator ensures that the env is sharable. Optional in most cases.
>>> env = SerialEnv(2, make_env)  # Makes 2 identical copies of the Pendulum env, runs them on the same process serially
>>> env = ParallelEnv(2, make_env)  # Makes 2 identical copies of the Pendulum env, runs them on dedicated processes
>>> from torchrl.envs import DMControlEnv
>>> env = ParallelEnv(2, [
...     lambda: DMControlEnv("humanoid", "stand"),
...     lambda: DMControlEnv("humanoid", "walk")])  # Creates two independent copies of Humanoid, one that walks one that stands
>>> rollout = env.rollout(10)  # executes 10 random steps in the environment
>>> rollout[0]  # data for Humanoid stand
TensorDict(
    fields={
        action: Tensor(shape=torch.Size([10, 21]), device=cpu, dtype=torch.float64, is_shared=False),
        com_velocity: Tensor(shape=torch.Size([10, 3]), device=cpu, dtype=torch.float64, is_shared=False),
        done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        extremities: Tensor(shape=torch.Size([10, 12]), device=cpu, dtype=torch.float64, is_shared=False),
        head_height: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.float64, is_shared=False),
        joint_angles: Tensor(shape=torch.Size([10, 21]), device=cpu, dtype=torch.float64, is_shared=False),
        next: TensorDict(
            fields={
                com_velocity: Tensor(shape=torch.Size([10, 3]), device=cpu, dtype=torch.float64, is_shared=False),
                done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                extremities: Tensor(shape=torch.Size([10, 12]), device=cpu, dtype=torch.float64, is_shared=False),
                head_height: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.float64, is_shared=False),
                joint_angles: Tensor(shape=torch.Size([10, 21]), device=cpu, dtype=torch.float64, is_shared=False),
                reward: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.float64, is_shared=False),
                terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                torso_vertical: Tensor(shape=torch.Size([10, 3]), device=cpu, dtype=torch.float64, is_shared=False),
                truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                velocity: Tensor(shape=torch.Size([10, 27]), device=cpu, dtype=torch.float64, is_shared=False)},
            batch_size=torch.Size([10]),
            device=cpu,
            is_shared=False),
        terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        torso_vertical: Tensor(shape=torch.Size([10, 3]), device=cpu, dtype=torch.float64, is_shared=False),
        truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        velocity: Tensor(shape=torch.Size([10, 27]), device=cpu, dtype=torch.float64, is_shared=False)},
    batch_size=torch.Size([10]),
    device=cpu,
    is_shared=False)
>>> rollout[1]  # data for Humanoid walk
TensorDict(
    fields={
        action: Tensor(shape=torch.Size([10, 21]), device=cpu, dtype=torch.float64, is_shared=False),
        com_velocity: Tensor(shape=torch.Size([10, 3]), device=cpu, dtype=torch.float64, is_shared=False),
        done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        extremities: Tensor(shape=torch.Size([10, 12]), device=cpu, dtype=torch.float64, is_shared=False),
        head_height: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.float64, is_shared=False),
        joint_angles: Tensor(shape=torch.Size([10, 21]), device=cpu, dtype=torch.float64, is_shared=False),
        next: TensorDict(
            fields={
                com_velocity: Tensor(shape=torch.Size([10, 3]), device=cpu, dtype=torch.float64, is_shared=False),
                done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                extremities: Tensor(shape=torch.Size([10, 12]), device=cpu, dtype=torch.float64, is_shared=False),
                head_height: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.float64, is_shared=False),
                joint_angles: Tensor(shape=torch.Size([10, 21]), device=cpu, dtype=torch.float64, is_shared=False),
                reward: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.float64, is_shared=False),
                terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                torso_vertical: Tensor(shape=torch.Size([10, 3]), device=cpu, dtype=torch.float64, is_shared=False),
                truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                velocity: Tensor(shape=torch.Size([10, 27]), device=cpu, dtype=torch.float64, is_shared=False)},
            batch_size=torch.Size([10]),
            device=cpu,
            is_shared=False),
        terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        torso_vertical: Tensor(shape=torch.Size([10, 3]), device=cpu, dtype=torch.float64, is_shared=False),
        truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        velocity: Tensor(shape=torch.Size([10, 27]), device=cpu, dtype=torch.float64, is_shared=False)},
    batch_size=torch.Size([10]),
    device=cpu,
    is_shared=False)
>>> # serial_for_single to avoid creating parallel envs if not necessary
>>> env = ParallelEnv(1, make_env, serial_for_single=True)
>>> assert isinstance(env, SerialEnv)  # serial_for_single allows you to avoid creating parallel envs when not necessary

Warning

TorchRL’s ParallelEnv is quite stringent when it comes to env specs, since these are used to build shared memory buffers for inter-process communication. As such, we encourage users to first run a check of the env specs with check_env_specs():

>>> from torchrl.envs import check_env_specs
>>> env = make_env()
>>> check_env_specs(env) # if this passes without error you're good to go!
>>> penv = ParallelEnv(2, make_env)

In particular, gym-like envs with info-dict readers may be difficult to share across processes if the spec is not properly set, which is hard to do automatically. Check set_info_dict_reader() for more information. Here is a short example:

>>> from torchrl.envs import GymEnv, set_gym_backend, check_env_specs, TransformedEnv, TensorDictPrimer
>>> import torch
>>> env = GymEnv("HalfCheetah-v4")
>>> env.rollout(3)  # no info registered, this env passes check_env_specs
TensorDict(
    fields={
        action: Tensor(shape=torch.Size([10, 6]), device=cpu, dtype=torch.float32, is_shared=False),
        done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        next: TensorDict(
            fields={
                done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([10, 17]), device=cpu, dtype=torch.float64, is_shared=False),
                reward: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.float32, is_shared=False),
                terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
            batch_size=torch.Size([10]),
            device=cpu,
            is_shared=False),
        observation: Tensor(shape=torch.Size([10, 17]), device=cpu, dtype=torch.float64, is_shared=False),
        terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
    batch_size=torch.Size([10]),
    device=cpu,
    is_shared=False)
>>> check_env_specs(env)  # succeeds!
>>> env.set_info_dict_reader()  # sets the default info_dict reader
>>> env.rollout(10)  # because the info_dict is empty at reset time, we're missing the root infos!
TensorDict(
    fields={
        action: Tensor(shape=torch.Size([10, 6]), device=cpu, dtype=torch.float32, is_shared=False),
        done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        next: TensorDict(
            fields={
                done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([10, 17]), device=cpu, dtype=torch.float64, is_shared=False),
                reward: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.float32, is_shared=False),
                reward_ctrl: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False),
                reward_run: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False),
                terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                x_position: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False),
                x_velocity: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False)},
            batch_size=torch.Size([10]),
            device=cpu,
            is_shared=False),
        observation: Tensor(shape=torch.Size([10, 17]), device=cpu, dtype=torch.float64, is_shared=False),
        terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
    batch_size=torch.Size([10]),
    device=cpu,
    is_shared=False)
>>> check_env_specs(env)  # This check now fails! We should not use an env constructed like this in a parallel env
>>> # This ad-hoc fix registers the info-spec for reset. It is wrapped inside `env.auto_register_info_dict()`
>>> env_fixed = TransformedEnv(env, TensorDictPrimer(env.info_dict_reader[0].info_spec))
>>> env_fixed.rollout(10)
TensorDict(
    fields={
        action: Tensor(shape=torch.Size([10, 6]), device=cpu, dtype=torch.float32, is_shared=False),
        done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        next: TensorDict(
            fields={
                done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([10, 17]), device=cpu, dtype=torch.float64, is_shared=False),
                reward: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.float32, is_shared=False),
                reward_ctrl: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False),
                reward_run: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False),
                terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                x_position: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False),
                x_velocity: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False)},
            batch_size=torch.Size([10]),
            device=cpu,
            is_shared=False),
        observation: Tensor(shape=torch.Size([10, 17]), device=cpu, dtype=torch.float64, is_shared=False),
        reward_ctrl: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False),
        reward_run: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False),
        terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        x_position: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False),
        x_velocity: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.float64, is_shared=False)},
    batch_size=torch.Size([10]),
    device=cpu,
    is_shared=False)
>>> check_env_specs(env_fixed)  # Succeeds! This env can be used within a parallel env!

Related classes and methods: auto_register_info_dict() and default_info_dict_reader.

Warning

The choice of the devices where ParallelEnv needs to be executed can drastically influence its performance. The rule of thumbs is:

• If the base environment (backend, e.g., Gym) is executed on CPU, the sub-environments should be executed on CPU and the data should be passed via shared physical memory.

• If the base environment is (or can be) executed on CUDA, the sub-environments should be placed on CUDA too.

• If a CUDA device is available and the policy is to be executed on CUDA, the ParallelEnv device should be set to CUDA.

Therefore, supposing a CUDA device is available, we have the following scenarios:

>>> # The sub-envs are executed on CPU, but the policy is on GPU
>>> env = ParallelEnv(N, MyEnv(..., device="cpu"), device="cuda")
>>> # The sub-envs are executed on CUDA
>>> env = ParallelEnv(N, MyEnv(..., device="cuda"), device="cuda")
>>> # this will create the exact same environment
>>> env = ParallelEnv(N, MyEnv(..., device="cuda"))
>>> # If no cuda device is available
>>> env = ParallelEnv(N, MyEnv(..., device="cpu"))

Warning

ParallelEnv disable gradients in all operations (step(), reset() and step_and_maybe_reset()) because gradients cannot be passed through multiprocessing.Pipe objects. Only SerialEnv will support backpropagation.

property action_key: NestedKey

The action key of an environment.

By default, this will be “action”.

If there is more than one action key in the environment, this function will raise an exception.

property action_keys: List[NestedKey]

The action keys of an environment.

By default, there will only be one key named “action”.

Keys are sorted by depth in the data tree.

property action_spec: TensorSpec

The action spec.

The action_spec is always stored as a composite spec.

If the action spec is provided as a simple spec, this will be returned.

>>> env.action_spec = Unbounded(1)
>>> env.action_spec
UnboundedContinuous(
    shape=torch.Size([1]),
    space=ContinuousBox(
        low=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True),
        high=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True)),
    device=cpu,
    dtype=torch.float32,
    domain=continuous)

If the action spec is provided as a composite spec and contains only one leaf, this function will return just the leaf.

>>> env.action_spec = Composite({"nested": {"action": Unbounded(1)}})
>>> env.action_spec
UnboundedContinuous(
    shape=torch.Size([1]),
    space=ContinuousBox(
        low=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True),
        high=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True)),
    device=cpu,
    dtype=torch.float32,
    domain=continuous)

If the action spec is provided as a composite spec and has more than one leaf, this function will return the whole spec.

>>> env.action_spec = Composite({"nested": {"action": Unbounded(1), "another_action": Categorical(1)}})
>>> env.action_spec
Composite(
    nested: Composite(
        action: UnboundedContinuous(
            shape=torch.Size([1]),
            space=ContinuousBox(
                low=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True),
                high=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True)),
            device=cpu,
            dtype=torch.float32,
            domain=continuous),
        another_action: Categorical(
            shape=torch.Size([]),
            space=DiscreteBox(n=1),
            device=cpu,
            dtype=torch.int64,
            domain=discrete), device=cpu, shape=torch.Size([])), device=cpu, shape=torch.Size([]))

To retrieve the full spec passed, use:

>>> env.input_spec["full_action_spec"]

This property is mutable.

Examples

>>> from torchrl.envs.libs.gym import GymEnv
>>> env = GymEnv("Pendulum-v1")
>>> env.action_spec
BoundedContinuous(
    shape=torch.Size([1]),
    space=ContinuousBox(
        low=Tensor(shape=torch.Size([1]), device=cpu, dtype=torch.float32, contiguous=True),
        high=Tensor(shape=torch.Size([1]), device=cpu, dtype=torch.float32, contiguous=True)),
    device=cpu,
    dtype=torch.float32,
    domain=continuous)

add_module(name: str, module: Optional[Module]) → None

Add a child module to the current module.

The module can be accessed as an attribute using the given name.

Parameters:

• name (str) – name of the child module. The child module can be accessed from this module using the given name

• module (Module) – child module to be added to the module.

add_truncated_keys()

Adds truncated keys to the environment.

append_transform(transform: 'Transform' | Callable[[TensorDictBase], TensorDictBase]) → EnvBase

Returns a transformed environment where the callable/transform passed is applied.

Parameters:

transform (Transform or Callable[[TensorDictBase], TensorDictBase]) – the transform to apply to the environment.

Examples

>>> from torchrl.envs import GymEnv
>>> import torch
>>> env = GymEnv("CartPole-v1")
>>> loc = 0.5
>>> scale = 1.0
>>> transform = lambda data: data.set("observation", (data.get("observation") - loc)/scale)
>>> env = env.append_transform(transform=transform)
>>> print(env)
TransformedEnv(
    env=GymEnv(env=CartPole-v1, batch_size=torch.Size([]), device=cpu),
    transform=_CallableTransform(keys=[]))

apply(fn: Callable[[Module], None]) → T

Apply fn recursively to every submodule (as returned by .children()) as well as self.

Typical use includes initializing the parameters of a model (see also torch.nn.init).

Parameters:

fn (Module -> None) – function to be applied to each submodule

Returns:

self

Return type:

Module

Example:

>>> @torch.no_grad()
>>> def init_weights(m):
>>>     print(m)
>>>     if type(m) == nn.Linear:
>>>         m.weight.fill_(1.0)
>>>         print(m.weight)
>>> net = nn.Sequential(nn.Linear(2, 2), nn.Linear(2, 2))
>>> net.apply(init_weights)
Linear(in_features=2, out_features=2, bias=True)
Parameter containing:
tensor([[1., 1.],
        [1., 1.]], requires_grad=True)
Linear(in_features=2, out_features=2, bias=True)
Parameter containing:
tensor([[1., 1.],
        [1., 1.]], requires_grad=True)
Sequential(
  (0): Linear(in_features=2, out_features=2, bias=True)
  (1): Linear(in_features=2, out_features=2, bias=True)
)

property batch_dims: int

Number of batch dimensions of the env.

property batch_locked: bool

Whether the environment can be used with a batch size different from the one it was initialized with or not.

If True, the env needs to be used with a tensordict having the same batch size as the env. batch_locked is an immutable property.

property batch_size: Size

Number of envs batched in this environment instance organised in a torch.Size() object.

Environment may be similar or different but it is assumed that they have little if not no interactions between them (e.g., multi-task or batched execution in parallel).

bfloat16() → T

Casts all floating point parameters and buffers to bfloat16 datatype.

Note

This method modifies the module in-place.

Returns:

self

Return type:

Module

buffers(recurse: bool = True) → Iterator[Tensor]

Return an iterator over module buffers.

Parameters:

recurse (bool) – if True, then yields buffers of this module and all submodules. Otherwise, yields only buffers that are direct members of this module.

Yields:

torch.Tensor – module buffer

Example:

>>> # xdoctest: +SKIP("undefined vars")
>>> for buf in model.buffers():
>>>     print(type(buf), buf.size())
<class 'torch.Tensor'> (20L,)
<class 'torch.Tensor'> (20L, 1L, 5L, 5L)

children() → Iterator[Module]

Return an iterator over immediate children modules.

Yields:

Module – a child module

compile(*args, **kwargs)

Compile this Module’s forward using torch.compile().

This Module’s __call__ method is compiled and all arguments are passed as-is to torch.compile().

See torch.compile() for details on the arguments for this function.

cpu() → T

Move all model parameters and buffers to the CPU.

Note

This method modifies the module in-place.

Returns:

self

Return type:

Module

cuda(device: Optional[Union[int, device]] = None) → T

Move all model parameters and buffers to the GPU.

This also makes associated parameters and buffers different objects. So it should be called before constructing optimizer if the module will live on GPU while being optimized.

Note

This method modifies the module in-place.

Parameters:

device (int, optional) – if specified, all parameters will be copied to that device

Returns:

self

Return type:

Module

property done_key

The done key of an environment.

By default, this will be “done”.

If there is more than one done key in the environment, this function will raise an exception.

property done_keys: List[NestedKey]

The done keys of an environment.

By default, there will only be one key named “done”.

Keys are sorted by depth in the data tree.

property done_keys_groups

A list of done keys, grouped as the reset keys.

This is a list of lists. The outer list has the length of reset keys, the inner lists contain the done keys (eg, done and truncated) that can be read to determine a reset when it is absent.

property done_spec: TensorSpec

The done spec.

The done_spec is always stored as a composite spec.

If the done spec is provided as a simple spec, this will be returned.

>>> env.done_spec = Categorical(2, dtype=torch.bool)
>>> env.done_spec
Categorical(
    shape=torch.Size([]),
    space=DiscreteBox(n=2),
    device=cpu,
    dtype=torch.bool,
    domain=discrete)

If the done spec is provided as a composite spec and contains only one leaf, this function will return just the leaf.

>>> env.done_spec = Composite({"nested": {"done": Categorical(2, dtype=torch.bool)}})
>>> env.done_spec
Categorical(
    shape=torch.Size([]),
    space=DiscreteBox(n=2),
    device=cpu,
    dtype=torch.bool,
    domain=discrete)

If the done spec is provided as a composite spec and has more than one leaf, this function will return the whole spec.

>>> env.done_spec = Composite({"nested": {"done": Categorical(2, dtype=torch.bool), "another_done": Categorical(2, dtype=torch.bool)}})
>>> env.done_spec
Composite(
    nested: Composite(
        done: Categorical(
            shape=torch.Size([]),
            space=DiscreteBox(n=2),
            device=cpu,
            dtype=torch.bool,
            domain=discrete),
        another_done: Categorical(
            shape=torch.Size([]),
            space=DiscreteBox(n=2),
            device=cpu,
            dtype=torch.bool,
            domain=discrete), device=cpu, shape=torch.Size([])), device=cpu, shape=torch.Size([]))

To always retrieve the full spec passed, use:

>>> env.output_spec["full_done_spec"]

This property is mutable.

Examples

>>> from torchrl.envs.libs.gym import GymEnv
>>> env = GymEnv("Pendulum-v1")
>>> env.done_spec
Categorical(
    shape=torch.Size([1]),
    space=DiscreteBox(n=2),
    device=cpu,
    dtype=torch.bool,
    domain=discrete)

double() → T

Casts all floating point parameters and buffers to double datatype.

Note

This method modifies the module in-place.

Returns:

self

Return type:

Module

empty_cache()

Erases all the cached values.

For regular envs, the key lists (reward, done etc) are cached, but in some cases they may change during the execution of the code (eg, when adding a transform).

eval() → T

Set the module in evaluation mode.

This has any effect only on certain modules. See documentations of particular modules for details of their behaviors in training/evaluation mode, if they are affected, e.g. Dropout, BatchNorm, etc.

This is equivalent with self.train(False).

See Locally disabling gradient computation for a comparison between .eval() and several similar mechanisms that may be confused with it.

Returns:

self

Return type:

Module

extra_repr() → str

Set the extra representation of the module.

To print customized extra information, you should re-implement this method in your own modules. Both single-line and multi-line strings are acceptable.

fake_tensordict() → TensorDictBase

Returns a fake tensordict with key-value pairs that match in shape, device and dtype what can be expected during an environment rollout.

float() → T

Casts all floating point parameters and buffers to float datatype.

Note

This method modifies the module in-place.

Returns:

self

Return type:

Module

forward(tensordict: TensorDictBase) → TensorDictBase

Define the computation performed at every call.

Should be overridden by all subclasses.

Note

Although the recipe for forward pass needs to be defined within this function, one should call the Module instance afterwards instead of this since the former takes care of running the registered hooks while the latter silently ignores them.

property full_action_spec: Composite

The full action spec.

full_action_spec is a Composite` instance that contains all the action entries.

Examples

>>> from torchrl.envs import BraxEnv
>>> for envname in BraxEnv.available_envs:
...     break
>>> env = BraxEnv(envname)
>>> env.full_action_spec
Composite(
    action: BoundedContinuous(
        shape=torch.Size([8]),
        space=ContinuousBox(
            low=Tensor(shape=torch.Size([8]), device=cpu, dtype=torch.float32, contiguous=True),
            high=Tensor(shape=torch.Size([8]), device=cpu, dtype=torch.float32, contiguous=True)),
        device=cpu,
        dtype=torch.float32,
        domain=continuous), device=cpu, shape=torch.Size([]))

property full_done_spec: Composite

The full done spec.

full_done_spec is a Composite` instance that contains all the done entries. It can be used to generate fake data with a structure that mimics the one obtained at runtime.

Examples

>>> import gymnasium
>>> from torchrl.envs import GymWrapper
>>> env = GymWrapper(gymnasium.make("Pendulum-v1"))
>>> env.full_done_spec
Composite(
    done: Categorical(
        shape=torch.Size([1]),
        space=DiscreteBox(n=2),
        device=cpu,
        dtype=torch.bool,
        domain=discrete),
    truncated: Categorical(
        shape=torch.Size([1]),
        space=DiscreteBox(n=2),
        device=cpu,
        dtype=torch.bool,
        domain=discrete), device=cpu, shape=torch.Size([]))

property full_reward_spec: Composite

The full reward spec.

full_reward_spec is a Composite` instance that contains all the reward entries.

Examples

>>> import gymnasium
>>> from torchrl.envs import GymWrapper, TransformedEnv, RenameTransform
>>> base_env = GymWrapper(gymnasium.make("Pendulum-v1"))
>>> env = TransformedEnv(base_env, RenameTransform("reward", ("nested", "reward")))
>>> env.full_reward_spec
Composite(
    nested: Composite(
        reward: UnboundedContinuous(
            shape=torch.Size([1]),
            space=ContinuousBox(
                low=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True),
                high=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True)),
            device=cpu,
            dtype=torch.float32,
            domain=continuous), device=None, shape=torch.Size([])), device=cpu, shape=torch.Size([]))

property full_state_spec: Composite

The full state spec.

full_state_spec is a Composite` instance that contains all the state entries (ie, the input data that is not action).

Examples

>>> from torchrl.envs import BraxEnv
>>> for envname in BraxEnv.available_envs:
...     break
>>> env = BraxEnv(envname)
>>> env.full_state_spec
Composite(
    state: Composite(
        pipeline_state: Composite(
            q: UnboundedContinuous(
                shape=torch.Size([15]),
                space=None,
                device=cpu,
                dtype=torch.float32,
                domain=continuous),
    [...], device=cpu, shape=torch.Size([])), device=cpu, shape=torch.Size([])), device=cpu, shape=torch.Size([]))

get_buffer(target: str) → Tensor

Return the buffer given by target if it exists, otherwise throw an error.

See the docstring for get_submodule for a more detailed explanation of this method’s functionality as well as how to correctly specify target.

Parameters:

target – The fully-qualified string name of the buffer to look for. (See get_submodule for how to specify a fully-qualified string.)

Returns:

The buffer referenced by target

Return type:

torch.Tensor

Raises:

AttributeError – If the target string references an invalid path or resolves to something that is not a buffer

get_extra_state() → Any

Return any extra state to include in the module’s state_dict.

Implement this and a corresponding set_extra_state() for your module if you need to store extra state. This function is called when building the module’s state_dict().

Note that extra state should be picklable to ensure working serialization of the state_dict. We only provide provide backwards compatibility guarantees for serializing Tensors; other objects may break backwards compatibility if their serialized pickled form changes.

Returns:

Any extra state to store in the module’s state_dict

Return type:

object

get_parameter(target: str) → Parameter

Return the parameter given by target if it exists, otherwise throw an error.

See the docstring for get_submodule for a more detailed explanation of this method’s functionality as well as how to correctly specify target.

Parameters:

target – The fully-qualified string name of the Parameter to look for. (See get_submodule for how to specify a fully-qualified string.)

Returns:

The Parameter referenced by target

Return type:

torch.nn.Parameter

Raises:

AttributeError – If the target string references an invalid path or resolves to something that is not an nn.Parameter

get_submodule(target: str) → Module

Return the submodule given by target if it exists, otherwise throw an error.

For example, let’s say you have an nn.Module A that looks like this:

A(
    (net_b): Module(
        (net_c): Module(
            (conv): Conv2d(16, 33, kernel_size=(3, 3), stride=(2, 2))
        )
        (linear): Linear(in_features=100, out_features=200, bias=True)
    )
)

(The diagram shows an nn.Module A. A has a nested submodule net_b, which itself has two submodules net_c and linear. net_c then has a submodule conv.)

To check whether or not we have the linear submodule, we would call get_submodule("net_b.linear"). To check whether we have the conv submodule, we would call get_submodule("net_b.net_c.conv").

The runtime of get_submodule is bounded by the degree of module nesting in target. A query against named_modules achieves the same result, but it is O(N) in the number of transitive modules. So, for a simple check to see if some submodule exists, get_submodule should always be used.

Parameters:

target – The fully-qualified string name of the submodule to look for. (See above example for how to specify a fully-qualified string.)

Returns:

The submodule referenced by target

Return type:

torch.nn.Module

Raises:

AttributeError – If the target string references an invalid path or resolves to something that is not an nn.Module

half() → T

Casts all floating point parameters and buffers to half datatype.

Note

This method modifies the module in-place.

Returns:

self

Return type:

Module

property input_spec: TensorSpec

Input spec.

The composite spec containing all specs for data input to the environments.

It contains:

• “full_action_spec”: the spec of the input actions

• “full_state_spec”: the spec of all other environment inputs

This attibute is locked and should be read-only. Instead, to set the specs contained in it, use the respective properties.

Examples

>>> from torchrl.envs.libs.gym import GymEnv
>>> env = GymEnv("Pendulum-v1")
>>> env.input_spec
Composite(
    full_state_spec: None,
    full_action_spec: Composite(
        action: BoundedContinuous(
            shape=torch.Size([1]),
            space=ContinuousBox(
                low=Tensor(shape=torch.Size([1]), device=cpu, dtype=torch.float32, contiguous=True),
                high=Tensor(shape=torch.Size([1]), device=cpu, dtype=torch.float32, contiguous=True)),
            device=cpu,
            dtype=torch.float32,
            domain=continuous), device=cpu, shape=torch.Size([])), device=cpu, shape=torch.Size([]))

ipu(device: Optional[Union[int, device]] = None) → T

Move all model parameters and buffers to the IPU.

This also makes associated parameters and buffers different objects. So it should be called before constructing optimizer if the module will live on IPU while being optimized.

Note

This method modifies the module in-place.

Parameters:

device (int, optional) – if specified, all parameters will be copied to that device

Returns:

self

Return type:

Module

load_state_dict(*args, **kwargs)

Copy parameters and buffers from state_dict into this module and its descendants.

If strict is True, then the keys of state_dict must exactly match the keys returned by this module’s state_dict() function.

Warning

If assign is True the optimizer must be created after the call to load_state_dict unless get_swap_module_params_on_conversion() is True.

Parameters:

• state_dict (dict) – a dict containing parameters and persistent buffers.

• strict (bool, optional) – whether to strictly enforce that the keys in state_dict match the keys returned by this module’s state_dict() function. Default: True

• assign (bool, optional) – When False, the properties of the tensors in the current module are preserved while when True, the properties of the Tensors in the state dict are preserved. The only exception is the requires_grad field of Default: ``False`

Returns:

• missing_keys is a list of str containing any keys that are expected

  by this module but missing from the provided state_dict.

• unexpected_keys is a list of str containing the keys that are not

  expected by this module but present in the provided state_dict.

Return type:

NamedTuple with missing_keys and unexpected_keys fields

Note

If a parameter or buffer is registered as None and its corresponding key exists in state_dict, load_state_dict() will raise a RuntimeError.

maybe_reset(tensordict: TensorDictBase) → TensorDictBase

Checks the done keys of the input tensordict and, if needed, resets the environment where it is done.

Parameters:

tensordict (TensorDictBase) – a tensordict coming from the output of step_mdp().

Returns:

A tensordict that is identical to the input where the environment was not reset and contains the new reset data where the environment was reset.

modules() → Iterator[Module]

Return an iterator over all modules in the network.

Yields:

Module – a module in the network

Note

Duplicate modules are returned only once. In the following example, l will be returned only once.

Example:

>>> l = nn.Linear(2, 2)
>>> net = nn.Sequential(l, l)
>>> for idx, m in enumerate(net.modules()):
...     print(idx, '->', m)

0 -> Sequential(
  (0): Linear(in_features=2, out_features=2, bias=True)
  (1): Linear(in_features=2, out_features=2, bias=True)
)
1 -> Linear(in_features=2, out_features=2, bias=True)

mtia(device: Optional[Union[int, device]] = None) → T

Move all model parameters and buffers to the MTIA.

This also makes associated parameters and buffers different objects. So it should be called before constructing optimizer if the module will live on MTIA while being optimized.

Note

This method modifies the module in-place.

Parameters:

device (int, optional) – if specified, all parameters will be copied to that device

Returns:

self

Return type:

Module

named_buffers(prefix: str = '', recurse: bool = True, remove_duplicate: bool = True) → Iterator[Tuple[str, Tensor]]

Return an iterator over module buffers, yielding both the name of the buffer as well as the buffer itself.

Parameters:

• prefix (str) – prefix to prepend to all buffer names.

• recurse (bool, optional) – if True, then yields buffers of this module and all submodules. Otherwise, yields only buffers that are direct members of this module. Defaults to True.

• remove_duplicate (bool, optional) – whether to remove the duplicated buffers in the result. Defaults to True.

Yields:

(str, torch.Tensor) – Tuple containing the name and buffer

Example:

>>> # xdoctest: +SKIP("undefined vars")
>>> for name, buf in self.named_buffers():
>>>     if name in ['running_var']:
>>>         print(buf.size())

named_children() → Iterator[Tuple[str, Module]]

Return an iterator over immediate children modules, yielding both the name of the module as well as the module itself.

Yields:

(str, Module) – Tuple containing a name and child module

Example:

>>> # xdoctest: +SKIP("undefined vars")
>>> for name, module in model.named_children():
>>>     if name in ['conv4', 'conv5']:
>>>         print(module)

named_modules(memo: Optional[Set[Module]] = None, prefix: str = '', remove_duplicate: bool = True)

Return an iterator over all modules in the network, yielding both the name of the module as well as the module itself.

Parameters:

• memo – a memo to store the set of modules already added to the result

• prefix – a prefix that will be added to the name of the module

• remove_duplicate – whether to remove the duplicated module instances in the result or not

Yields:

(str, Module) – Tuple of name and module

Note

Duplicate modules are returned only once. In the following example, l will be returned only once.

Example:

>>> l = nn.Linear(2, 2)
>>> net = nn.Sequential(l, l)
>>> for idx, m in enumerate(net.named_modules()):
...     print(idx, '->', m)

0 -> ('', Sequential(
  (0): Linear(in_features=2, out_features=2, bias=True)
  (1): Linear(in_features=2, out_features=2, bias=True)
))
1 -> ('0', Linear(in_features=2, out_features=2, bias=True))

named_parameters(prefix: str = '', recurse: bool = True, remove_duplicate: bool = True) → Iterator[Tuple[str, Parameter]]

Return an iterator over module parameters, yielding both the name of the parameter as well as the parameter itself.

Parameters:

• prefix (str) – prefix to prepend to all parameter names.

• recurse (bool) – if True, then yields parameters of this module and all submodules. Otherwise, yields only parameters that are direct members of this module.

• remove_duplicate (bool, optional) – whether to remove the duplicated parameters in the result. Defaults to True.

Yields:

(str, Parameter) – Tuple containing the name and parameter

Example:

>>> # xdoctest: +SKIP("undefined vars")
>>> for name, param in self.named_parameters():
>>>     if name in ['bias']:
>>>         print(param.size())

property observation_spec: Composite

Observation spec.

Must be a torchrl.data.Composite instance. The keys listed in the spec are directly accessible after reset and step.

In TorchRL, even though they are not properly speaking “observations” all info, states, results of transforms etc. outputs from the environment are stored in the observation_spec.

Therefore, "observation_spec" should be thought as a generic data container for environment outputs that are not done or reward data.

Examples

>>> from torchrl.envs.libs.gym import GymEnv
>>> env = GymEnv("Pendulum-v1")
>>> env.observation_spec
Composite(
    observation: BoundedContinuous(
        shape=torch.Size([3]),
        space=ContinuousBox(
            low=Tensor(shape=torch.Size([3]), device=cpu, dtype=torch.float32, contiguous=True),
            high=Tensor(shape=torch.Size([3]), device=cpu, dtype=torch.float32, contiguous=True)),
        device=cpu,
        dtype=torch.float32,
        domain=continuous), device=cpu, shape=torch.Size([]))

property output_spec: TensorSpec

Output spec.

The composite spec containing all specs for data output from the environments.

It contains:

• “full_reward_spec”: the spec of reward

• “full_done_spec”: the spec of done

• “full_observation_spec”: the spec of all other environment outputs

This attibute is locked and should be read-only. Instead, to set the specs contained in it, use the respective properties.

Examples

>>> from torchrl.envs.libs.gym import GymEnv
>>> env = GymEnv("Pendulum-v1")
>>> env.output_spec
Composite(
    full_reward_spec: Composite(
        reward: UnboundedContinuous(
            shape=torch.Size([1]),
            space=None,
            device=cpu,
            dtype=torch.float32,
            domain=continuous), device=cpu, shape=torch.Size([])),
    full_observation_spec: Composite(
        observation: BoundedContinuous(
            shape=torch.Size([3]),
            space=ContinuousBox(
                low=Tensor(shape=torch.Size([3]), device=cpu, dtype=torch.float32, contiguous=True),
                high=Tensor(shape=torch.Size([3]), device=cpu, dtype=torch.float32, contiguous=True)),
            device=cpu,
            dtype=torch.float32,
            domain=continuous), device=cpu, shape=torch.Size([])),
    full_done_spec: Composite(
        done: Categorical(
            shape=torch.Size([1]),
            space=DiscreteBox(n=2),
            device=cpu,
            dtype=torch.bool,
            domain=discrete), device=cpu, shape=torch.Size([])), device=cpu, shape=torch.Size([]))

parameters(recurse: bool = True) → Iterator[Parameter]

Return an iterator over module parameters.

This is typically passed to an optimizer.

Parameters:

recurse (bool) – if True, then yields parameters of this module and all submodules. Otherwise, yields only parameters that are direct members of this module.

Yields:

Parameter – module parameter

Example:

>>> # xdoctest: +SKIP("undefined vars")
>>> for param in model.parameters():
>>>     print(type(param), param.size())
<class 'torch.Tensor'> (20L,)
<class 'torch.Tensor'> (20L, 1L, 5L, 5L)

rand_action(tensordict: Optional[TensorDictBase] = None)

Performs a random action given the action_spec attribute.

Parameters:

tensordict (TensorDictBase, optional) – tensordict where the resulting action should be written.

Returns:

a tensordict object with the “action” entry updated with a random sample from the action-spec.

rand_step(tensordict: Optional[TensorDictBase] = None) → TensorDictBase

Performs a random step in the environment given the action_spec attribute.

Parameters:

tensordict (TensorDictBase, optional) – tensordict where the resulting info should be written.

Returns:

a tensordict object with the new observation after a random step in the environment. The action will be stored with the “action” key.

register_backward_hook(hook: Callable[[Module, Union[Tuple[Tensor, ...], Tensor], Union[Tuple[Tensor, ...], Tensor]], Union[None, Tuple[Tensor, ...], Tensor]]) → RemovableHandle

Register a backward hook on the module.

This function is deprecated in favor of register_full_backward_hook() and the behavior of this function will change in future versions.

Returns:

a handle that can be used to remove the added hook by calling handle.remove()

Return type:

torch.utils.hooks.RemovableHandle

register_buffer(name: str, tensor: Optional[Tensor], persistent: bool = True) → None

Add a buffer to the module.

This is typically used to register a buffer that should not to be considered a model parameter. For example, BatchNorm’s running_mean is not a parameter, but is part of the module’s state. Buffers, by default, are persistent and will be saved alongside parameters. This behavior can be changed by setting persistent to False. The only difference between a persistent buffer and a non-persistent buffer is that the latter will not be a part of this module’s state_dict.

Buffers can be accessed as attributes using given names.

Parameters:

• name (str) – name of the buffer. The buffer can be accessed from this module using the given name

• tensor (Tensor or None) – buffer to be registered. If None, then operations that run on buffers, such as cuda, are ignored. If None, the buffer is not included in the module’s state_dict.

• persistent (bool) – whether the buffer is part of this module’s state_dict.

Example:

>>> # xdoctest: +SKIP("undefined vars")
>>> self.register_buffer('running_mean', torch.zeros(num_features))

register_forward_hook(hook: Union[Callable[[T, Tuple[Any, ...], Any], Optional[Any]], Callable[[T, Tuple[Any, ...], Dict[str, Any], Any], Optional[Any]]], *, prepend: bool = False, with_kwargs: bool = False, always_call: bool = False) → RemovableHandle

Register a forward hook on the module.

The hook will be called every time after forward() has computed an output.

If with_kwargs is False or not specified, the input contains only the positional arguments given to the module. Keyword arguments won’t be passed to the hooks and only to the forward. The hook can modify the output. It can modify the input inplace but it will not have effect on forward since this is called after forward() is called. The hook should have the following signature:

hook(module, args, output) -> None or modified output

If with_kwargs is True, the forward hook will be passed the kwargs given to the forward function and be expected to return the output possibly modified. The hook should have the following signature:

hook(module, args, kwargs, output) -> None or modified output

Parameters:

• hook (Callable) – The user defined hook to be registered.

• prepend (bool) – If True, the provided hook will be fired before all existing forward hooks on this torch.nn.modules.Module. Otherwise, the provided hook will be fired after all existing forward hooks on this torch.nn.modules.Module. Note that global forward hooks registered with register_module_forward_hook() will fire before all hooks registered by this method. Default: False

• with_kwargs (bool) – If True, the hook will be passed the kwargs given to the forward function. Default: False

• always_call (bool) – If True the hook will be run regardless of whether an exception is raised while calling the Module. Default: False

Returns:

a handle that can be used to remove the added hook by calling handle.remove()

Return type:

torch.utils.hooks.RemovableHandle

register_forward_pre_hook(hook: Union[Callable[[T, Tuple[Any, ...]], Optional[Any]], Callable[[T, Tuple[Any, ...], Dict[str, Any]], Optional[Tuple[Any, Dict[str, Any]]]]], *, prepend: bool = False, with_kwargs: bool = False) → RemovableHandle

Register a forward pre-hook on the module.

The hook will be called every time before forward() is invoked.

If with_kwargs is false or not specified, the input contains only the positional arguments given to the module. Keyword arguments won’t be passed to the hooks and only to the forward. The hook can modify the input. User can either return a tuple or a single modified value in the hook. We will wrap the value into a tuple if a single value is returned (unless that value is already a tuple). The hook should have the following signature:

hook(module, args) -> None or modified input

If with_kwargs is true, the forward pre-hook will be passed the kwargs given to the forward function. And if the hook modifies the input, both the args and kwargs should be returned. The hook should have the following signature:

hook(module, args, kwargs) -> None or a tuple of modified input and kwargs

Parameters:

• hook (Callable) – The user defined hook to be registered.

• prepend (bool) – If true, the provided hook will be fired before all existing forward_pre hooks on this torch.nn.modules.Module. Otherwise, the provided hook will be fired after all existing forward_pre hooks on this torch.nn.modules.Module. Note that global forward_pre hooks registered with register_module_forward_pre_hook() will fire before all hooks registered by this method. Default: False

• with_kwargs (bool) – If true, the hook will be passed the kwargs given to the forward function. Default: False

Returns:

a handle that can be used to remove the added hook by calling handle.remove()

Return type:

torch.utils.hooks.RemovableHandle

register_full_backward_hook(hook: Callable[[Module, Union[Tuple[Tensor, ...], Tensor], Union[Tuple[Tensor, ...], Tensor]], Union[None, Tuple[Tensor, ...], Tensor]], prepend: bool = False) → RemovableHandle

Register a backward hook on the module.

The hook will be called every time the gradients with respect to a module are computed, i.e. the hook will execute if and only if the gradients with respect to module outputs are computed. The hook should have the following signature:

hook(module, grad_input, grad_output) -> tuple(Tensor) or None

The grad_input and grad_output are tuples that contain the gradients with respect to the inputs and outputs respectively. The hook should not modify its arguments, but it can optionally return a new gradient with respect to the input that will be used in place of grad_input in subsequent computations. grad_input will only correspond to the inputs given as positional arguments and all kwarg arguments are ignored. Entries in grad_input and grad_output will be None for all non-Tensor arguments.

For technical reasons, when this hook is applied to a Module, its forward function will receive a view of each Tensor passed to the Module. Similarly the caller will receive a view of each Tensor returned by the Module’s forward function.

Warning

Modifying inputs or outputs inplace is not allowed when using backward hooks and will raise an error.

Parameters:

• hook (Callable) – The user-defined hook to be registered.

• prepend (bool) – If true, the provided hook will be fired before all existing backward hooks on this torch.nn.modules.Module. Otherwise, the provided hook will be fired after all existing backward hooks on this torch.nn.modules.Module. Note that global backward hooks registered with register_module_full_backward_hook() will fire before all hooks registered by this method.

Returns:

a handle that can be used to remove the added hook by calling handle.remove()

Return type:

torch.utils.hooks.RemovableHandle

register_full_backward_pre_hook(hook: Callable[[Module, Union[Tuple[Tensor, ...], Tensor]], Union[None, Tuple[Tensor, ...], Tensor]], prepend: bool = False) → RemovableHandle

Register a backward pre-hook on the module.

The hook will be called every time the gradients for the module are computed. The hook should have the following signature:

hook(module, grad_output) -> tuple[Tensor] or None

The grad_output is a tuple. The hook should not modify its arguments, but it can optionally return a new gradient with respect to the output that will be used in place of grad_output in subsequent computations. Entries in grad_output will be None for all non-Tensor arguments.

For technical reasons, when this hook is applied to a Module, its forward function will receive a view of each Tensor passed to the Module. Similarly the caller will receive a view of each Tensor returned by the Module’s forward function.

Warning

Modifying inputs inplace is not allowed when using backward hooks and will raise an error.

Parameters:

• hook (Callable) – The user-defined hook to be registered.

• prepend (bool) – If true, the provided hook will be fired before all existing backward_pre hooks on this torch.nn.modules.Module. Otherwise, the provided hook will be fired after all existing backward_pre hooks on this torch.nn.modules.Module. Note that global backward_pre hooks registered with register_module_full_backward_pre_hook() will fire before all hooks registered by this method.

Returns:

a handle that can be used to remove the added hook by calling handle.remove()

Return type:

torch.utils.hooks.RemovableHandle

classmethod register_gym(id: str, *, entry_point: Callable | None = None, transform: 'Transform' | None = None, info_keys: List[NestedKey] | None = None, backend: str = None, to_numpy: bool = False, reward_threshold: float | None = None, nondeterministic: bool = False, max_episode_steps: int | None = None, order_enforce: bool = True, autoreset: bool = False, disable_env_checker: bool = False, apply_api_compatibility: bool = False, **kwargs)

Registers an environment in gym(nasium).

This method is designed with the following scopes in mind:

• Incorporate a TorchRL-first environment in a framework that uses Gym;

• Incorporate another environment (eg, DeepMind Control, Brax, Jumanji, …) in a framework that uses Gym.

Parameters:

id (str) – the name of the environment. Should follow the gym naming convention.

Keyword Arguments:

• entry_point (callable, optional) –

  the entry point to build the environment. If none is passed, the parent class will be used as entry point. Typically, this is used to register an environment that does not necessarily inherit from the base being used:

  >>> from torchrl.envs import DMControlEnv
  >>> DMControlEnv.register_gym("DMC-cheetah-v0", env_name="cheetah", task="run")
  >>> # equivalently
  >>> EnvBase.register_gym("DMC-cheetah-v0", entry_point=DMControlEnv, env_name="cheetah", task="run")
  

• transform (torchrl.envs.Transform) – a transform (or list of transforms within a torchrl.envs.Compose instance) to be used with the env. This arg can be passed during a call to make() (see example below).

• info_keys (List[NestedKey], optional) –

  if provided, these keys will be used to build the info dictionary and will be excluded from the observation keys. This arg can be passed during a call to make() (see example below).

  Warning

  It may be the case that using info_keys makes a spec empty because the content has been moved to the info dictionary. Gym does not like empty Dict in the specs, so this empty content should be removed with RemoveEmptySpecs.

• backend (str, optional) – the backend. Can be either “gym” or “gymnasium” or any other backend compatible with set_gym_backend.

• to_numpy (bool, optional) – if True, the result of calls to step and reset will be mapped to numpy arrays. Defaults to False (results are tensors). This arg can be passed during a call to make() (see example below).

• reward_threshold (float, optional) – [Gym kwarg] The reward threshold considered to have learnt an environment.

• nondeterministic (bool, optional) – [Gym kwarg If the environment is nondeterministic (even with knowledge of the initial seed and all actions). Defaults to False.

• max_episode_steps (int, optional) – [Gym kwarg] The maximum number of episodes steps before truncation. Used by the Time Limit wrapper.

• order_enforce (bool, optional) – [Gym >= 0.14] Whether the order enforcer wrapper should be applied to ensure users run functions in the correct order. Defaults to True.

• autoreset (bool, optional) – [Gym >= 0.14] Whether the autoreset wrapper should be added such that reset does not need to be called. Defaults to False.

• disable_env_checker – [Gym >= 0.14] Whether the environment checker should be disabled for the environment. Defaults to False.

• apply_api_compatibility – [Gym >= 0.26] If to apply the StepAPICompatibility wrapper. Defaults to False.

• **kwargs – arbitrary keyword arguments which are passed to the environment constructor.

Note

TorchRL’s environment do not have the concept of an "info" dictionary, as TensorDict offers all the storage requirements deemed necessary in most training settings. Still, you can use the info_keys argument to have a fine grained control over what is deemed to be considered as an observation and what should be seen as info.

Examples

>>> # Register the "cheetah" env from DMControl with the "run" task
>>> from torchrl.envs import DMControlEnv
>>> import torch
>>> DMControlEnv.register_gym("DMC-cheetah-v0", to_numpy=False, backend="gym", env_name="cheetah", task_name="run")
>>> import gym
>>> envgym = gym.make("DMC-cheetah-v0")
>>> envgym.seed(0)
>>> torch.manual_seed(0)
>>> envgym.reset()
({'position': tensor([-0.0855,  0.0215, -0.0881, -0.0412, -0.1101,  0.0080,  0.0254,  0.0424],
       dtype=torch.float64), 'velocity': tensor([ 1.9609e-02, -1.9776e-04, -1.6347e-03,  3.3842e-02,  2.5338e-02,
         3.3064e-02,  1.0381e-04,  7.6656e-05,  1.0204e-02],
       dtype=torch.float64)}, {})
>>> envgym.step(envgym.action_space.sample())
({'position': tensor([-0.0833,  0.0275, -0.0612, -0.0770, -0.1256,  0.0082,  0.0186,  0.0476],
       dtype=torch.float64), 'velocity': tensor([ 0.2221,  0.2256,  0.5930,  2.6937, -3.5865, -1.5479,  0.0187, -0.6825,
         0.5224], dtype=torch.float64)}, tensor([0.0018], dtype=torch.float64), tensor([False]), tensor([False]), {})
>>> # same environment with observation stacked
>>> from torchrl.envs import CatTensors
>>> envgym = gym.make("DMC-cheetah-v0", transform=CatTensors(in_keys=["position", "velocity"], out_key="observation"))
>>> envgym.reset()
({'observation': tensor([-0.1005,  0.0335, -0.0268,  0.0133, -0.0627,  0.0074, -0.0488, -0.0353,
        -0.0075, -0.0069,  0.0098, -0.0058,  0.0033, -0.0157, -0.0004, -0.0381,
        -0.0452], dtype=torch.float64)}, {})
>>> # same environment with numpy observations
>>> envgym = gym.make("DMC-cheetah-v0", transform=CatTensors(in_keys=["position", "velocity"], out_key="observation"), to_numpy=True)
>>> envgym.reset()
({'observation': array([-0.11355747,  0.04257728,  0.00408397,  0.04155852, -0.0389733 ,
       -0.01409826, -0.0978704 , -0.08808327,  0.03970837,  0.00535434,
       -0.02353762,  0.05116226,  0.02788907,  0.06848346,  0.05154399,
        0.0371798 ,  0.05128025])}, {})
>>> # If gymnasium is installed, we can register the environment there too.
>>> DMControlEnv.register_gym("DMC-cheetah-v0", to_numpy=False, backend="gymnasium", env_name="cheetah", task_name="run")
>>> import gymnasium
>>> envgym = gymnasium.make("DMC-cheetah-v0")
>>> envgym.seed(0)
>>> torch.manual_seed(0)
>>> envgym.reset()
({'position': tensor([-0.0855,  0.0215, -0.0881, -0.0412, -0.1101,  0.0080,  0.0254,  0.0424],
       dtype=torch.float64), 'velocity': tensor([ 1.9609e-02, -1.9776e-04, -1.6347e-03,  3.3842e-02,  2.5338e-02,
         3.3064e-02,  1.0381e-04,  7.6656e-05,  1.0204e-02],
       dtype=torch.float64)}, {})

Note

This feature also works for stateless environments (eg, BraxEnv).

>>> import gymnasium
>>> import torch
>>> from tensordict import TensorDict
>>> from torchrl.envs import BraxEnv, SelectTransform
>>>
>>> # get action for dydactic purposes
>>> env = BraxEnv("ant", batch_size=[2])
>>> env.set_seed(0)
>>> torch.manual_seed(0)
>>> td = env.rollout(10)
>>>
>>> actions = td.get("action")
>>>
>>> # register env
>>> env.register_gym("Brax-Ant-v0", env_name="ant", batch_size=[2], info_keys=["state"])
>>> gym_env = gymnasium.make("Brax-Ant-v0")
>>> gym_env.seed(0)
>>> torch.manual_seed(0)
>>>
>>> gym_env.reset()
>>> obs = []
>>> for i in range(10):
...     obs, reward, terminated, truncated, info = gym_env.step(td[..., i].get("action"))

register_load_state_dict_post_hook(hook)

Register a post-hook to be run after module’s load_state_dict() is called.

It should have the following signature::

hook(module, incompatible_keys) -> None

The module argument is the current module that this hook is registered on, and the incompatible_keys argument is a NamedTuple consisting of attributes missing_keys and unexpected_keys. missing_keys is a list of str containing the missing keys and unexpected_keys is a list of str containing the unexpected keys.

The given incompatible_keys can be modified inplace if needed.

Note that the checks performed when calling load_state_dict() with strict=True are affected by modifications the hook makes to missing_keys or unexpected_keys, as expected. Additions to either set of keys will result in an error being thrown when strict=True, and clearing out both missing and unexpected keys will avoid an error.

Returns:

a handle that can be used to remove the added hook by calling handle.remove()

Return type:

torch.utils.hooks.RemovableHandle

register_load_state_dict_pre_hook(hook)

Register a pre-hook to be run before module’s load_state_dict() is called.

It should have the following signature::

hook(module, state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs) -> None # noqa: B950

Parameters:

hook (Callable) – Callable hook that will be invoked before loading the state dict.

register_module(name: str, module: Optional[Module]) → None

Alias for add_module().

register_parameter(name: str, param: Optional[Parameter]) → None

Add a parameter to the module.

The parameter can be accessed as an attribute using given name.

Parameters:

• name (str) – name of the parameter. The parameter can be accessed from this module using the given name

• param (Parameter or None) – parameter to be added to the module. If None, then operations that run on parameters, such as cuda, are ignored. If None, the parameter is not included in the module’s state_dict.

register_state_dict_post_hook(hook)

Register a post-hook for the state_dict() method.

It should have the following signature::

hook(module, state_dict, prefix, local_metadata) -> None

The registered hooks can modify the state_dict inplace.

register_state_dict_pre_hook(hook)

Register a pre-hook for the state_dict() method.

It should have the following signature::

hook(module, prefix, keep_vars) -> None

The registered hooks can be used to perform pre-processing before the state_dict call is made.

requires_grad_(requires_grad: bool = True) → T

Change if autograd should record operations on parameters in this module.

This method sets the parameters’ requires_grad attributes in-place.

This method is helpful for freezing part of the module for finetuning or training parts of a model individually (e.g., GAN training).

See Locally disabling gradient computation for a comparison between .requires_grad_() and several similar mechanisms that may be confused with it.

Parameters:

requires_grad (bool) – whether autograd should record operations on parameters in this module. Default: True.

Returns:

self

Return type:

Module

reset(tensordict: Optional[TensorDictBase] = None, **kwargs) → TensorDictBase

Resets the environment.

As for step and _step, only the private method _reset should be overwritten by EnvBase subclasses.

Parameters:

• tensordict (TensorDictBase, optional) – tensordict to be used to contain the resulting new observation. In some cases, this input can also be used to pass argument to the reset function.

• kwargs (optional) – other arguments to be passed to the native reset function.

Returns:

a tensordict (or the input tensordict, if any), modified in place with the resulting observations.

property reset_keys: List[NestedKey]

Returns a list of reset keys.

Reset keys are keys that indicate partial reset, in batched, multitask or multiagent settings. They are structured as (*prefix, "_reset") where prefix is a (possibly empty) tuple of strings pointing to a tensordict location where a done state can be found.

Keys are sorted by depth in the data tree.

property reward_key

The reward key of an environment.

By default, this will be “reward”.

If there is more than one reward key in the environment, this function will raise an exception.

property reward_keys: List[NestedKey]

The reward keys of an environment.

By default, there will only be one key named “reward”.

Keys are sorted by depth in the data tree.

property reward_spec: TensorSpec

The reward spec.

The reward_spec is always stored as a composite spec.

If the reward spec is provided as a simple spec, this will be returned.

>>> env.reward_spec = Unbounded(1)
>>> env.reward_spec
UnboundedContinuous(
    shape=torch.Size([1]),
    space=ContinuousBox(
        low=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True),
        high=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True)),
    device=cpu,
    dtype=torch.float32,
    domain=continuous)

If the reward spec is provided as a composite spec and contains only one leaf, this function will return just the leaf.

>>> env.reward_spec = Composite({"nested": {"reward": Unbounded(1)}})
>>> env.reward_spec
UnboundedContinuous(
    shape=torch.Size([1]),
    space=ContinuousBox(
        low=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True),
        high=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True)),
    device=cpu,
    dtype=torch.float32,
    domain=continuous)

If the reward spec is provided as a composite spec and has more than one leaf, this function will return the whole spec.

>>> env.reward_spec = Composite({"nested": {"reward": Unbounded(1), "another_reward": Categorical(1)}})
>>> env.reward_spec
Composite(
    nested: Composite(
        reward: UnboundedContinuous(
            shape=torch.Size([1]),
            space=ContinuousBox(
                low=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True),
                high=Tensor(shape=torch.Size([]), device=cpu, dtype=torch.float32, contiguous=True)),
            device=cpu,
            dtype=torch.float32,
            domain=continuous),
        another_reward: Categorical(
            shape=torch.Size([]),
            space=DiscreteBox(n=1),
            device=cpu,
            dtype=torch.int64,
            domain=discrete), device=cpu, shape=torch.Size([])), device=cpu, shape=torch.Size([]))

To retrieve the full spec passed, use:

>>> env.output_spec["full_reward_spec"]

This property is mutable.

Examples

>>> from torchrl.envs.libs.gym import GymEnv
>>> env = GymEnv("Pendulum-v1")
>>> env.reward_spec
UnboundedContinuous(
    shape=torch.Size([1]),
    space=None,
    device=cpu,
    dtype=torch.float32,
    domain=continuous)

rollout(max_steps: int, policy: Optional[Callable[[TensorDictBase], TensorDictBase]] = None, callback: Optional[Callable[[TensorDictBase, ...], Any]] = None, *, auto_reset: bool = True, auto_cast_to_device: bool = False, break_when_any_done: Optional[bool] = None, break_when_all_done: Optional[bool] = None, return_contiguous: bool = True, tensordict: Optional[TensorDictBase] = None, set_truncated: bool = False, out=None, trust_policy: bool = False) → TensorDictBase

Executes a rollout in the environment.

The function will return as soon as any of the contained environments reaches any of the done states.

Parameters:

• max_steps (int) – maximum number of steps to be executed. The actual number of steps can be smaller if the environment reaches a done state before max_steps have been executed.

• policy (callable, optional) – callable to be called to compute the desired action. If no policy is provided, actions will be called using env.rand_step(). The policy can be any callable that reads either a tensordict or the entire sequence of observation entries __sorted as__ the env.observation_spec.keys(). Defaults to None.

• callback (Callable[[TensorDict], Any], optional) – function to be called at each iteration with the given TensorDict. Defaults to None. The output of callback will not be collected, it is the user responsibility to save any result within the callback call if data needs to be carried over beyond the call to rollout.

Keyword Arguments:

• auto_reset (bool, optional) – if True, the contained environments will be reset before starting the rollout. If False, then the rollout will continue from a previous state, which requires the tensordict argument to be passed with the previous rollout. Default is True.

• auto_cast_to_device (bool, optional) – if True, the device of the tensordict is automatically cast to the policy device before the policy is used. Default is False.

• break_when_any_done (bool) – if True, break when any of the contained environments reaches any of the done states. If False, then the done environments are reset automatically. Default is True.

• break_when_all_done (bool, optional) – if True, break if all of the contained environments reach any of the done states. If False, break if at least one environment reaches any of the done states. Default is False.

• return_contiguous (bool) – if False, a LazyStackedTensorDict will be returned. Default is True.

• tensordict (TensorDict, optional) – if auto_reset is False, an initial tensordict must be provided. Rollout will check if this tensordict has done flags and reset the environment in those dimensions (if needed). This normally should not occur if tensordict is the output of a reset, but can occur if tensordict is the last step of a previous rollout. A tensordict can also be provided when auto_reset=True if metadata need to be passed to the reset method, such as a batch-size or a device for stateless environments.

• set_truncated (bool, optional) – if True, "truncated" and "done" keys will be set to True after completion of the rollout. If no "truncated" is found within the done_spec, an exception is raised. Truncated keys can be set through env.add_truncated_keys. Defaults to False.

• trust_policy (bool, optional) – if True, a non-TensorDictModule policy will be trusted to be assumed to be compatible with the collector. This defaults to True for CudaGraphModules and False otherwise.

Returns:

TensorDict object containing the resulting trajectory.

The data returned will be marked with a “time” dimension name for the last dimension of the tensordict (at the env.ndim index).

rollout is quite handy to display what the data structure of the environment looks like.

Examples

>>> # Using rollout without a policy
>>> from torchrl.envs.libs.gym import GymEnv
>>> from torchrl.envs.transforms import TransformedEnv, StepCounter
>>> env = TransformedEnv(GymEnv("Pendulum-v1"), StepCounter(max_steps=20))
>>> rollout = env.rollout(max_steps=1000)
>>> print(rollout)
TensorDict(
    fields={
        action: Tensor(shape=torch.Size([20, 1]), device=cpu, dtype=torch.float32, is_shared=False),
        done: Tensor(shape=torch.Size([20, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        next: TensorDict(
            fields={
                done: Tensor(shape=torch.Size([20, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([20, 3]), device=cpu, dtype=torch.float32, is_shared=False),
                reward: Tensor(shape=torch.Size([20, 1]), device=cpu, dtype=torch.float32, is_shared=False),
                step_count: Tensor(shape=torch.Size([20, 1]), device=cpu, dtype=torch.int64, is_shared=False),
                truncated: Tensor(shape=torch.Size([20, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
            batch_size=torch.Size([20]),
            device=cpu,
            is_shared=False),
        observation: Tensor(shape=torch.Size([20, 3]), device=cpu, dtype=torch.float32, is_shared=False),
        step_count: Tensor(shape=torch.Size([20, 1]), device=cpu, dtype=torch.int64, is_shared=False),
        truncated: Tensor(shape=torch.Size([20, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
    batch_size=torch.Size([20]),
    device=cpu,
    is_shared=False)
>>> print(rollout.names)
['time']
>>> # with envs that contain more dimensions
>>> from torchrl.envs import SerialEnv
>>> env = SerialEnv(3, lambda: TransformedEnv(GymEnv("Pendulum-v1"), StepCounter(max_steps=20)))
>>> rollout = env.rollout(max_steps=1000)
>>> print(rollout)
TensorDict(
    fields={
        action: Tensor(shape=torch.Size([3, 20, 1]), device=cpu, dtype=torch.float32, is_shared=False),
        done: Tensor(shape=torch.Size([3, 20, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        next: TensorDict(
            fields={
                done: Tensor(shape=torch.Size([3, 20, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([3, 20, 3]), device=cpu, dtype=torch.float32, is_shared=False),
                reward: Tensor(shape=torch.Size([3, 20, 1]), device=cpu, dtype=torch.float32, is_shared=False),
                step_count: Tensor(shape=torch.Size([3, 20, 1]), device=cpu, dtype=torch.int64, is_shared=False),
                truncated: Tensor(shape=torch.Size([3, 20, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
            batch_size=torch.Size([3, 20]),
            device=cpu,
            is_shared=False),
        observation: Tensor(shape=torch.Size([3, 20, 3]), device=cpu, dtype=torch.float32, is_shared=False),
        step_count: Tensor(shape=torch.Size([3, 20, 1]), device=cpu, dtype=torch.int64, is_shared=False),
        truncated: Tensor(shape=torch.Size([3, 20, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
    batch_size=torch.Size([3, 20]),
    device=cpu,
    is_shared=False)
>>> print(rollout.names)
[None, 'time']

Using a policy (a regular Module or a TensorDictModule) is also easy:

Examples

>>> from torch import nn
>>> env = GymEnv("CartPole-v1", categorical_action_encoding=True)
>>> class ArgMaxModule(nn.Module):
...     def forward(self, values):
...         return values.argmax(-1)
>>> n_obs = env.observation_spec["observation"].shape[-1]
>>> n_act = env.action_spec.n
>>> # A deterministic policy
>>> policy = nn.Sequential(
...     nn.Linear(n_obs, n_act),
...     ArgMaxModule())
>>> env.rollout(max_steps=10, policy=policy)
TensorDict(
    fields={
        action: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.int64, is_shared=False),
        done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        next: TensorDict(
            fields={
                done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([10, 4]), device=cpu, dtype=torch.float32, is_shared=False),
                reward: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.float32, is_shared=False),
                terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
            batch_size=torch.Size([10]),
            device=cpu,
            is_shared=False),
        observation: Tensor(shape=torch.Size([10, 4]), device=cpu, dtype=torch.float32, is_shared=False),
        terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
    batch_size=torch.Size([10]),
    device=cpu,
    is_shared=False)
>>> # Under the hood, rollout will wrap the policy in a TensorDictModule
>>> # To speed things up we can do that ourselves
>>> from tensordict.nn import TensorDictModule
>>> policy = TensorDictModule(policy, in_keys=list(env.observation_spec.keys()), out_keys=["action"])
>>> env.rollout(max_steps=10, policy=policy)
TensorDict(
    fields={
        action: Tensor(shape=torch.Size([10]), device=cpu, dtype=torch.int64, is_shared=False),
        done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        next: TensorDict(
            fields={
                done: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([10, 4]), device=cpu, dtype=torch.float32, is_shared=False),
                reward: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.float32, is_shared=False),
                terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
            batch_size=torch.Size([10]),
            device=cpu,
            is_shared=False),
        observation: Tensor(shape=torch.Size([10, 4]), device=cpu, dtype=torch.float32, is_shared=False),
        terminated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        truncated: Tensor(shape=torch.Size([10, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
    batch_size=torch.Size([10]),
    device=cpu,
    is_shared=False)

In some instances, contiguous tensordict cannot be obtained because they cannot be stacked. This can happen when the data returned at each step may have a different shape, or when different environments are executed together. In that case, return_contiguous=False will cause the returned tensordict to be a lazy stack of tensordicts:

Examples of non-contiguous rollout:

>>> rollout = env.rollout(4, return_contiguous=False)
>>> print(rollout)
LazyStackedTensorDict(
    fields={
        action: Tensor(shape=torch.Size([3, 4, 1]), device=cpu, dtype=torch.float32, is_shared=False),
        done: Tensor(shape=torch.Size([3, 4, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        next: LazyStackedTensorDict(
            fields={
                done: Tensor(shape=torch.Size([3, 4, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([3, 4, 3]), device=cpu, dtype=torch.float32, is_shared=False),
                reward: Tensor(shape=torch.Size([3, 4, 1]), device=cpu, dtype=torch.float32, is_shared=False),
                step_count: Tensor(shape=torch.Size([3, 4, 1]), device=cpu, dtype=torch.int64, is_shared=False),
                truncated: Tensor(shape=torch.Size([3, 4, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
            batch_size=torch.Size([3, 4]),
            device=cpu,
            is_shared=False),
        observation: Tensor(shape=torch.Size([3, 4, 3]), device=cpu, dtype=torch.float32, is_shared=False),
        step_count: Tensor(shape=torch.Size([3, 4, 1]), device=cpu, dtype=torch.int64, is_shared=False),
        truncated: Tensor(shape=torch.Size([3, 4, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
    batch_size=torch.Size([3, 4]),
    device=cpu,
    is_shared=False)
    >>> print(rollout.names)
    [None, 'time']

Rollouts can be used in a loop to emulate data collection. To do so, you need to pass as input the last tensordict coming from the previous rollout after calling step_mdp() on it.

Examples of data collection rollouts:

>>> from torchrl.envs import GymEnv, step_mdp
>>> env = GymEnv("CartPole-v1")
>>> epochs = 10
>>> input_td = env.reset()
>>> for i in range(epochs):
...     rollout_td = env.rollout(
...         max_steps=100,
...         break_when_any_done=False,
...         auto_reset=False,
...         tensordict=input_td,
...     )
...     input_td = step_mdp(
...         rollout_td[..., -1],
...     )

set_extra_state(state: Any) → None

Set extra state contained in the loaded state_dict.

This function is called from load_state_dict() to handle any extra state found within the state_dict. Implement this function and a corresponding get_extra_state() for your module if you need to store extra state within its state_dict.

Parameters:

state (dict) – Extra state from the state_dict

set_seed(*args, **kwargs)

Sets the seed of the environment and returns the next seed to be used (which is the input seed if a single environment is present).

Parameters:

• seed (int) – seed to be set. The seed is set only locally in the environment. To handle the global seed, see manual_seed().

• static_seed (bool, optional) – if True, the seed is not incremented. Defaults to False

Returns:

i.e. the seed that should be used for another environment if created concomitantly to this environment.

Return type:

integer representing the “next seed”

set_submodule(target: str, module: Module) → None

Set the submodule given by target if it exists, otherwise throw an error.

For example, let’s say you have an nn.Module A that looks like this:

A(
    (net_b): Module(
        (net_c): Module(
            (conv): Conv2d(16, 33, kernel_size=(3, 3), stride=(2, 2))
        )
        (linear): Linear(in_features=100, out_features=200, bias=True)
    )
)

(The diagram shows an nn.Module A. A has a nested submodule net_b, which itself has two submodules net_c and linear. net_c then has a submodule conv.)

To overide the Conv2d with a new submodule Linear, you would call set_submodule("net_b.net_c.conv", nn.Linear(33, 16)).

Parameters:

• target – The fully-qualified string name of the submodule to look for. (See above example for how to specify a fully-qualified string.)

• module – The module to set the submodule to.

Raises:

• ValueError – If the target string is empty

• AttributeError – If the target string references an invalid path or resolves to something that is not an nn.Module

property shape

Equivalent to batch_size.

share_memory() → T

See torch.Tensor.share_memory_().

property single_action_spec: TensorSpec

Returns the action spec of the env as if it had no batch dimensions.

property single_done_spec: TensorSpec

Returns the done spec of the env as if it had no batch dimensions.

property single_full_action_spec: Composite

Returns the action spec of the env as if it had no batch dimensions.

property single_full_done_spec: Composite

Returns the done spec of the env as if it had no batch dimensions.

property single_full_observation_spec: Composite

Returns the observation spec of the env as if it had no batch dimensions.

property single_full_reward_spec: Composite

Returns the reward spec of the env as if it had no batch dimensions.

property single_full_state_spec: Composite

Returns the state spec of the env as if it had no batch dimensions.

property single_input_spec: Composite

Returns the input spec of the env as if it had no batch dimensions.

property single_observation_spec: Composite

Returns the observation spec of the env as if it had no batch dimensions.

property single_output_spec: Composite

Returns the output spec of the env as if it had no batch dimensions.

property single_reward_spec: TensorSpec

Returns the reward spec of the env as if it had no batch dimensions.

property single_state_spec: TensorSpec

Returns the state spec of the env as if it had no batch dimensions.

property specs: Composite

Returns a Composite container where all the environment are present.

This feature allows one to create an environment, retrieve all of the specs in a single data container and then erase the environment from the workspace.

state_dict(*args, **kwargs)

Return a dictionary containing references to the whole state of the module.

Both parameters and persistent buffers (e.g. running averages) are included. Keys are corresponding parameter and buffer names. Parameters and buffers set to None are not included.

Note

The returned object is a shallow copy. It contains references to the module’s parameters and buffers.

Warning

Currently state_dict() also accepts positional arguments for destination, prefix and keep_vars in order. However, this is being deprecated and keyword arguments will be enforced in future releases.

Warning

Please avoid the use of argument destination as it is not designed for end-users.

Parameters:

• destination (dict, optional) – If provided, the state of module will be updated into the dict and the same object is returned. Otherwise, an OrderedDict will be created and returned. Default: None.

• prefix (str, optional) – a prefix added to parameter and buffer names to compose the keys in state_dict. Default: ''.

• keep_vars (bool, optional) – by default the Tensor s returned in the state dict are detached from autograd. If it’s set to True, detaching will not be performed. Default: False.

Returns:

a dictionary containing a whole state of the module

Return type:

dict

Example:

>>> # xdoctest: +SKIP("undefined vars")
>>> module.state_dict().keys()
['bias', 'weight']

property state_keys: List[NestedKey]

The state keys of an environment.

By default, there will only be one key named “state”.

Keys are sorted by depth in the data tree.

property state_spec: Composite

State spec.

Must be a torchrl.data.Composite instance. The keys listed here should be provided as input alongside actions to the environment.

In TorchRL, even though they are not properly speaking “state” all inputs to the environment that are not actions are stored in the state_spec.

Therefore, "state_spec" should be thought as a generic data container for environment inputs that are not action data.

Examples

>>> from torchrl.envs import BraxEnv
>>> for envname in BraxEnv.available_envs:
...     break
>>> env = BraxEnv(envname)
>>> env.state_spec
Composite(
    state: Composite(
        pipeline_state: Composite(
            q: UnboundedContinuous(
                shape=torch.Size([15]),
                space=None,
                device=cpu,
                dtype=torch.float32,
                domain=continuous),
    [...], device=cpu, shape=torch.Size([])), device=cpu, shape=torch.Size([])), device=cpu, shape=torch.Size([]))

step(tensordict: TensorDictBase) → TensorDictBase

Makes a step in the environment.

Step accepts a single argument, tensordict, which usually carries an ‘action’ key which indicates the action to be taken. Step will call an out-place private method, _step, which is the method to be re-written by EnvBase subclasses.

Parameters:

tensordict (TensorDictBase) – Tensordict containing the action to be taken. If the input tensordict contains a "next" entry, the values contained in it will prevail over the newly computed values. This gives a mechanism to override the underlying computations.

Returns:

the input tensordict, modified in place with the resulting observations, done state and reward (+ others if needed).

step_and_maybe_reset(*args, **kwargs)

Runs a step in the environment and (partially) resets it if needed.

Parameters:

tensordict (TensorDictBase) – an input data structure for the step() method.

This method allows to easily code non-stopping rollout functions.

Examples

>>> from torchrl.envs import ParallelEnv, GymEnv
>>> def rollout(env, n):
...     data_ = env.reset()
...     result = []
...     for i in range(n):
...         data, data_ = env.step_and_maybe_reset(data_)
...         result.append(data)
...     return torch.stack(result)
>>> env = ParallelEnv(2, lambda: GymEnv("CartPole-v1"))
>>> print(rollout(env, 2))
TensorDict(
    fields={
        done: Tensor(shape=torch.Size([2, 2, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        next: TensorDict(
            fields={
                done: Tensor(shape=torch.Size([2, 2, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([2, 2, 4]), device=cpu, dtype=torch.float32, is_shared=False),
                reward: Tensor(shape=torch.Size([2, 2, 1]), device=cpu, dtype=torch.float32, is_shared=False),
                terminated: Tensor(shape=torch.Size([2, 2, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                truncated: Tensor(shape=torch.Size([2, 2, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
            batch_size=torch.Size([2, 2]),
            device=cpu,
            is_shared=False),
        observation: Tensor(shape=torch.Size([2, 2, 4]), device=cpu, dtype=torch.float32, is_shared=False),
        terminated: Tensor(shape=torch.Size([2, 2, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        truncated: Tensor(shape=torch.Size([2, 2, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
    batch_size=torch.Size([2, 2]),
    device=cpu,
    is_shared=False)

to(device: Union[device, str, int])

Move and/or cast the parameters and buffers.

This can be called as

to(device=None, dtype=None, non_blocking=False)

to(dtype, non_blocking=False)

to(tensor, non_blocking=False)

to(memory_format=torch.channels_last)

Its signature is similar to torch.Tensor.to(), but only accepts floating point or complex dtypes. In addition, this method will only cast the floating point or complex parameters and buffers to dtype (if given). The integral parameters and buffers will be moved device, if that is given, but with dtypes unchanged. When non_blocking is set, it tries to convert/move asynchronously with respect to the host if possible, e.g., moving CPU Tensors with pinned memory to CUDA devices.

See below for examples.

Note

This method modifies the module in-place.

Parameters:

• device (torch.device) – the desired device of the parameters and buffers in this module

• dtype (torch.dtype) – the desired floating point or complex dtype of the parameters and buffers in this module

• tensor (torch.Tensor) – Tensor whose dtype and device are the desired dtype and device for all parameters and buffers in this module

• memory_format (torch.memory_format) – the desired memory format for 4D parameters and buffers in this module (keyword only argument)

Returns:

self

Return type:

Module

Examples:

>>> # xdoctest: +IGNORE_WANT("non-deterministic")
>>> linear = nn.Linear(2, 2)
>>> linear.weight
Parameter containing:
tensor([[ 0.1913, -0.3420],
        [-0.5113, -0.2325]])
>>> linear.to(torch.double)
Linear(in_features=2, out_features=2, bias=True)
>>> linear.weight
Parameter containing:
tensor([[ 0.1913, -0.3420],
        [-0.5113, -0.2325]], dtype=torch.float64)
>>> # xdoctest: +REQUIRES(env:TORCH_DOCTEST_CUDA1)
>>> gpu1 = torch.device("cuda:1")
>>> linear.to(gpu1, dtype=torch.half, non_blocking=True)
Linear(in_features=2, out_features=2, bias=True)
>>> linear.weight
Parameter containing:
tensor([[ 0.1914, -0.3420],
        [-0.5112, -0.2324]], dtype=torch.float16, device='cuda:1')
>>> cpu = torch.device("cpu")
>>> linear.to(cpu)
Linear(in_features=2, out_features=2, bias=True)
>>> linear.weight
Parameter containing:
tensor([[ 0.1914, -0.3420],
        [-0.5112, -0.2324]], dtype=torch.float16)

>>> linear = nn.Linear(2, 2, bias=None).to(torch.cdouble)
>>> linear.weight
Parameter containing:
tensor([[ 0.3741+0.j,  0.2382+0.j],
        [ 0.5593+0.j, -0.4443+0.j]], dtype=torch.complex128)
>>> linear(torch.ones(3, 2, dtype=torch.cdouble))
tensor([[0.6122+0.j, 0.1150+0.j],
        [0.6122+0.j, 0.1150+0.j],
        [0.6122+0.j, 0.1150+0.j]], dtype=torch.complex128)

to_empty(*, device: Optional[Union[int, str, device]], recurse: bool = True) → T

Move the parameters and buffers to the specified device without copying storage.

Parameters:

• device (torch.device) – The desired device of the parameters and buffers in this module.

• recurse (bool) – Whether parameters and buffers of submodules should be recursively moved to the specified device.

Returns:

self

Return type:

Module

train(mode: bool = True) → T

Set the module in training mode.

This has any effect only on certain modules. See documentations of particular modules for details of their behaviors in training/evaluation mode, if they are affected, e.g. Dropout, BatchNorm, etc.

Parameters:

mode (bool) – whether to set training mode (True) or evaluation mode (False). Default: True.

Returns:

self

Return type:

Module

type(dst_type: Union[dtype, str]) → T

Casts all parameters and buffers to dst_type.

Note

This method modifies the module in-place.

Parameters:

dst_type (type or string) – the desired type

Returns:

self

Return type:

Module

update_kwargs(kwargs: Union[dict, List[dict]]) → None

Updates the kwargs of each environment given a dictionary or a list of dictionaries.

Parameters:

kwargs (dict or list of dict) – new kwargs to use with the environments

xpu(device: Optional[Union[int, device]] = None) → T

Move all model parameters and buffers to the XPU.

This also makes associated parameters and buffers different objects. So it should be called before constructing optimizer if the module will live on XPU while being optimized.

Note

This method modifies the module in-place.

Parameters:

device (int, optional) – if specified, all parameters will be copied to that device

Returns:

self

Return type:

Module

zero_grad(set_to_none: bool = True) → None

Reset gradients of all model parameters.

See similar function under torch.optim.Optimizer for more context.

Parameters:

set_to_none (bool) – instead of setting to zero, set the grads to None. See torch.optim.Optimizer.zero_grad() for details.