ray.rllib.evaluation.rollout_worker.RolloutWorker.compute_gradients

RolloutWorker.compute_gradients(samples: SampleBatch | MultiAgentBatch, single_agent: bool = None) → Tuple[List[Tuple[numpy.array | jnp.ndarray | tf.Tensor | torch.Tensor, numpy.array | jnp.ndarray | tf.Tensor | torch.Tensor]] | List[numpy.array | jnp.ndarray | tf.Tensor | torch.Tensor], dict]

Returns a gradient computed w.r.t the specified samples.

Uses the Policy’s/ies’ compute_gradients method(s) to perform the calculations. Skips policies that are not trainable as per self.is_policy_to_train().

Parameters:

samples – The SampleBatch or MultiAgentBatch to compute gradients for using this worker’s trainable policies.

Returns:

In the single-agent case, a tuple consisting of ModelGradients and info dict of the worker’s policy. In the multi-agent case, a tuple consisting of a dict mapping PolicyID to ModelGradients and a dict mapping PolicyID to extra metadata info. Note that the first return value (grads) can be applied as is to a compatible worker using the worker’s apply_gradients() method.

import gymnasium as gym
from ray.rllib.evaluation.rollout_worker import RolloutWorker
from ray.rllib.algorithms.ppo.ppo_tf_policy import PPOTF1Policy
worker = RolloutWorker(
  env_creator=lambda _: gym.make("CartPole-v1"),
  default_policy_class=PPOTF1Policy)
batch = worker.sample()
grads, info = worker.compute_gradients(samples)