reference/generated/torchrl.render.backends.MujocoStateReader

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MujocoStateReader

class torchrl.render.backends.MujocoStateReader

Reads simulator state from TorchRL-native and Gym MuJoCo environments.

The reader keeps simulator state separate from policy observations. It accepts environments exposing a get_state() method that returns a TensorDict or mapping with a "qpos" entry, as well as TorchRL GymWrapper instances around Gymnasium MuJoCo environments.

Examples

>>> from types import SimpleNamespace
>>> import numpy as np
>>> from torchrl.render.backends import MujocoStateReader
>>> env = SimpleNamespace(
...     data=SimpleNamespace(
...         qpos=np.array([0.0, 1.0]),
...         qvel=np.array([0.5, 0.0]),
...         time=0.25,
...     )
... )
>>> state = MujocoStateReader().capture(env)
>>> state["qpos"].tolist()
[0.0, 1.0]

capture(env: Any) → TensorDictBase

Returns a detached snapshot of the environment’s MuJoCo state.

Parameters:

env – TorchRL-native MuJoCo environment, Gym-backed MuJoCo environment, or object exposing MuJoCo data directly.

Returns:

A TensorDict containing qpos and any available qvel, act, ctrl, mocap_pos, mocap_quat, and time entries.

Raises:

• TypeError – If the environment does not expose a supported state.

• KeyError – If the exposed state does not contain qpos.

supports(env: Any) → bool

Returns whether env exposes a readable MuJoCo state.