RenameTransform

class torchrl.envs.transforms.RenameTransform(in_keys, out_keys, in_keys_inv=None, out_keys_inv=None, create_copy=False)

A transform to rename entries in the output tensordict (or input tensordict via the inverse keys).

Parameters:

• in_keys (sequence of NestedKey) – the entries to rename.

• out_keys (sequence of NestedKey) – the name of the entries after renaming.

• in_keys_inv (sequence of NestedKey, optional) – the entries to rename in the input tensordict, which will be passed to EnvBase._step().

• out_keys_inv (sequence of NestedKey, optional) – the names of the entries in the input tensordict after renaming.

• create_copy (bool, optional) – if True, the entries will be copied with a different name rather than being renamed. This allows for renaming immutable entries such as "reward" and "done".

Examples

>>> from torchrl.envs.libs.gym import GymEnv
>>> env = TransformedEnv(
...     GymEnv("Pendulum-v1"),
...     RenameTransform(["observation", ], ["stuff",], create_copy=False),
... )
>>> tensordict = env.rollout(3)
>>> print(tensordict)
TensorDict(
    fields={
        action: Tensor(shape=torch.Size([3, 1]), device=cpu, dtype=torch.float32, is_shared=False),
        done: Tensor(shape=torch.Size([3, 1]), device=cpu, dtype=torch.bool, is_shared=False),
        next: TensorDict(
            fields={
                done: Tensor(shape=torch.Size([3, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                reward: Tensor(shape=torch.Size([3, 1]), device=cpu, dtype=torch.float32, is_shared=False),
                stuff: Tensor(shape=torch.Size([3, 3]), device=cpu, dtype=torch.float32, is_shared=False)},
            batch_size=torch.Size([3]),
            device=cpu,
            is_shared=False),
        stuff: Tensor(shape=torch.Size([3, 3]), device=cpu, dtype=torch.float32, is_shared=False)},
    batch_size=torch.Size([3]),
    device=cpu,
    is_shared=False)
>>> # if the output is also an input, we need to rename if both ways:
>>> from torchrl.envs.libs.brax import BraxEnv
>>> env = TransformedEnv(
...     BraxEnv("fast"),
...     RenameTransform(["state"], ["newname"], ["state"], ["newname"])
... )
>>> _ = env.set_seed(1)
>>> tensordict = env.rollout(3)
>>> assert "newname" in tensordict.keys()
>>> assert "state" not in tensordict.keys()

forward(next_tensordict: TensorDictBase) → TensorDictBase

Reads the input tensordict, and for the selected keys, applies the transform.

By default, this method:

• calls directly _apply_transform().

• does not call _step() or _call().

This method is not called within env.step at any point. However, is is called within sample().

Note

forward also works with regular keyword arguments using dispatch to cast the args names to the keys.

Examples

>>> class TransformThatMeasuresBytes(Transform):
...     '''Measures the number of bytes in the tensordict, and writes it under `"bytes"`.'''
...     def __init__(self):
...         super().__init__(in_keys=[], out_keys=["bytes"])
...
...     def forward(self, tensordict: TensorDictBase) -> TensorDictBase:
...         bytes_in_td = tensordict.bytes()
...         tensordict["bytes"] = bytes
...         return tensordict
>>> t = TransformThatMeasuresBytes()
>>> env = env.append_transform(t) # works within envs
>>> t(TensorDict(a=0))  # Works offline too.

transform_input_spec(input_spec: Composite) → Composite

Transforms the input spec such that the resulting spec matches transform mapping.

Parameters:

input_spec (TensorSpec) – spec before the transform

Returns:

expected spec after the transform

transform_output_spec(output_spec: Composite) → Composite

Transforms the output spec such that the resulting spec matches transform mapping.

This method should generally be left untouched. Changes should be implemented using transform_observation_spec(), transform_reward_spec() and transform_full_done_spec(). :param output_spec: spec before the transform :type output_spec: TensorSpec

Returns:

expected spec after the transform