PettingZooWrapper¶

torchrl.envs.PettingZooWrapper(*args, **kwargs)[source]¶

PettingZoo environment wrapper.

To install petting zoo follow the guide here <https://github.com/Farama-Foundation/PettingZoo#installation>__.

This class is a general torchrl wrapper for all PettingZoo environments. It is able to wrap both pettingzoo.AECEnv and pettingzoo.ParallelEnv.

Let’s see how more in details:

In wrapped pettingzoo.ParallelEnv all agents will step at each environment step. If the number of agents during the task varies, please set use_mask=True. "mask" will be provided as an output in each group and should be used to mask out dead agents. The environment will be reset as soon as one agent is done (unless done_on_any is False).

In wrapped pettingzoo.AECEnv, at each step only one agent will act. For this reason, it is compulsory to set use_mask=True for this type of environment. "mask" will be provided as an output for each group and can be used to mask out non-acting agents. The environment will be reset only when all agents are done (unless done_on_any is True).

If there are any unavailable actions for an agent, the environment will also automatically update the mask of its action_spec and output an "action_mask" for each group to reflect the latest available actions. This should be passed to a masked distribution during training.

As a feature of torchrl multiagent, you are able to control the grouping of agents in your environment. You can group agents together (stacking their tensors) to leverage vectorization when passing them through the same neural network. You can split agents in different groups where they are heterogenous or should be processed by different neural networks. To group, you just need to pass a group_map at env constructiuon time.

By default, agents in pettingzoo will be grouped by name. For example, with agents ["agent_0","agent_1","agent_2","adversary_0"], the tensordicts will look like:

>>> print(env.rand_action(env.reset()))
TensorDict(
    fields={
        agent: TensorDict(
            fields={
                action: Tensor(shape=torch.Size([3, 9]), device=cpu, dtype=torch.int64, is_shared=False),
                action_mask: Tensor(shape=torch.Size([3, 9]), device=cpu, dtype=torch.bool, is_shared=False),
                done: Tensor(shape=torch.Size([3, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([3, 3, 3, 2]), device=cpu, dtype=torch.int8, is_shared=False),
                terminated: Tensor(shape=torch.Size([3, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                truncated: Tensor(shape=torch.Size([3, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
            batch_size=torch.Size([3]))},
        adversary: TensorDict(
            fields={
                action: Tensor(shape=torch.Size([1, 9]), device=cpu, dtype=torch.int64, is_shared=False),
                action_mask: Tensor(shape=torch.Size([1, 9]), device=cpu, dtype=torch.bool, is_shared=False),
                done: Tensor(shape=torch.Size([1, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([1, 3, 3, 2]), device=cpu, dtype=torch.int8, is_shared=False),
                terminated: Tensor(shape=torch.Size([1, 1]), device=cpu, dtype=torch.bool, is_shared=False),
                truncated: Tensor(shape=torch.Size([1, 1]), device=cpu, dtype=torch.bool, is_shared=False)},
            batch_size=torch.Size([1]))},
    batch_size=torch.Size([]))
>>> print(env.group_map)
{"agent": ["agent_0", "agent_1", "agent_2"], "adversary": ["adversary_0"]}

Otherwise, a group map can be specified or selected from some premade options. See torchrl.envs.utils.MarlGroupMapType for more info. For example, you can provide MarlGroupMapType.ONE_GROUP_PER_AGENT, telling that each agent should have its own tensordict (similar to the pettingzoo parallel API).

Grouping is useful for leveraging vectorization among agents whose data goes through the same neural network.

Parameters:

env (pettingzoo.utils.env.ParallelEnv or pettingzoo.utils.env.AECEnv) – the pettingzoo environment to wrap.
return_state (bool, optional) – whether to return the global state from pettingzoo (not available in all environments). Defaults to False.
group_map (MarlGroupMapType or Dict[str, List[str]]], optional) – how to group agents in tensordicts for input/output. By default, agents will be grouped by their name. Otherwise, a group map can be specified or selected from some premade options. See torchrl.envs.utils.MarlGroupMapType for more info.
use_mask (bool, optional) – whether the environment should output a "mask". This is compulsory in wrapped pettingzoo.AECEnv to mask out non-acting agents and should be also used for pettingzoo.ParallelEnv when the number of agents can vary. Defaults to False.
categorical_actions (bool, optional) – if the environments actions are discrete, whether to transform them to categorical or one-hot.
seed (int, optional) – the seed. Defaults to None.
done_on_any (bool, optional) – whether the environment’s done keys are set by aggregating the agent keys using any() (when True) or all() (when False). Default (None) is to use any() for parallel environments and all() for AEC ones.

Examples

>>> # Parallel env
>>> from torchrl.envs.libs.pettingzoo import PettingZooWrapper
>>> from pettingzoo.butterfly import pistonball_v6
>>> kwargs = {"n_pistons": 21, "continuous": True}
>>> env = PettingZooWrapper(
...     env=pistonball_v6.parallel_env(**kwargs),
...     return_state=True,
...     group_map=None, # Use default for parallel (all pistons grouped together)
... )
>>> print(env.group_map)
... {'piston': ['piston_0', 'piston_1', ..., 'piston_20']}
>>> env.rollout(10)
>>> # AEC env
>>> from pettingzoo.classic import tictactoe_v3
>>> from torchrl.envs.libs.pettingzoo import PettingZooWrapper
>>> from torchrl.envs.utils import MarlGroupMapType
>>> env = PettingZooWrapper(
...     env=tictactoe_v3.env(),
...     use_mask=True, # Must use it since one player plays at a time
...     group_map=None # # Use default for AEC (one group per player)
... )
>>> print(env.group_map)
... {'player_1': ['player_1'], 'player_2': ['player_2']}
>>> env.rollout(10)

PettingZooWrapper¶

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