[Feature] More flexibility in loading PettingZoo (#1817)

Author: matteobettini

torchrl/envs/libs/pettingzoo.py

@@ -6,6 +6,7 @@
 
 import copy
 import importlib
+import warnings
 from typing import Dict, List, Tuple, Union
 
 import torch
@@ -27,11 +28,54 @@
 def _get_envs():
     if not _has_pettingzoo:
         raise ImportError("PettingZoo is not installed in your virtual environment.")
-    from pettingzoo.utils.all_modules import all_environments
+    try:
+        from pettingzoo.utils.all_modules import all_environments
+    except ModuleNotFoundError as err:
+        warnings.warn(
+            f"PettingZoo failed to load all modules with error message {err}, trying to load individual modules."
+        )
+        all_environments = _load_available_envs()
 
     return list(all_environments.keys())
 
 
+def _load_available_envs() -> Dict:
+    all_environments = {}
+    try:
+        from pettingzoo.mpe.all_modules import mpe_environments
+
+        all_environments.update(mpe_environments)
+    except ModuleNotFoundError as err:
+        warnings.warn(f"MPE environments failed to load with error message {err}.")
+    try:
+        from pettingzoo.sisl.all_modules import sisl_environments
+
+        all_environments.update(sisl_environments)
+    except ModuleNotFoundError as err:
+        warnings.warn(f"SISL environments failed to load with error message {err}.")
+    try:
+        from pettingzoo.classic.all_modules import classic_environments
+
+        all_environments.update(classic_environments)
+    except ModuleNotFoundError as err:
+        warnings.warn(f"Classic environments failed to load with error message {err}.")
+    try:
+        from pettingzoo.atari.all_modules import atari_environments
+
+        all_environments.update(atari_environments)
+    except ModuleNotFoundError as err:
+        warnings.warn(f"Atari environments failed to load with error message {err}.")
+    try:
+        from pettingzoo.butterfly.all_modules import butterfly_environments
+
+        all_environments.update(butterfly_environments)
+    except ModuleNotFoundError as err:
+        warnings.warn(
+            f"Butterfly environments failed to load with error message {err}."
+        )
+    return all_environments
+
+
 class PettingZooWrapper(_EnvWrapper):
     """PettingZoo environment wrapper.
 
@@ -834,7 +878,8 @@ class PettingZooEnv(PettingZooWrapper):
     neural network.
 
     Args:
-        task (str): the name of the pettingzoo task to create (for example, "multiwalker_v9").
+        task (str): the name of the pettingzoo task to create in the "<env>/<task>" format (for example, "sisl/multiwalker_v9")
+            or "<task>" format (for example, "multiwalker_v9").
         parallel (bool): if to construct the ``pettingzoo.ParallelEnv`` version of the task or the ``pettingzoo.AECEnv``.
         return_state (bool, optional): whether to return the global state from pettingzoo
             (not available in all environments).  Defaults to ``False``.
@@ -919,7 +964,13 @@ def _build_env(
     ]:
         self.task_name = task
 
-        from pettingzoo.utils.all_modules import all_environments
+        try:
+            from pettingzoo.utils.all_modules import all_environments
+        except ModuleNotFoundError as err:
+            warnings.warn(
+                f"PettingZoo failed to load all modules with error message {err}, trying to load individual modules."
+            )
+            all_environments = _load_available_envs()
 
         if task not in all_environments:
             # Try looking at the literal translation of values
@@ -929,7 +980,9 @@ def _build_env(
                     task_module = value
                     break
             if task_module is None:
-                raise RuntimeError(f"Specified task not in {_get_envs()}")
+                raise RuntimeError(
+                    f"Specified task not in available environments {all_environments}"
+                )
         else:
             task_module = all_environments[task]