Revert "ENH: allow metadata["render_modes"] to be a set" (openai#251)

Author: pseudo-rnd-thoughts

docs/tutorials/environment_creation.py

@@ -100,7 +100,7 @@
 
 
 class GridWorldEnv(gym.Env):
-    metadata = {"render_modes": {"human", "rgb_array"}, "render_fps": 4}
+    metadata = {"render_modes": ["human", "rgb_array"], "render_fps": 4}
 
     def __init__(self, render_mode=None, size=5):
         self.size = size  # The size of the square grid
@@ -130,6 +130,7 @@ def __init__(self, render_mode=None, size=5):
             3: np.array([0, -1]),
         }
 
+        assert render_mode is None or render_mode in self.metadata["render_modes"]
         self.render_mode = render_mode
 
         """

gymnasium/core.py

@@ -47,7 +47,7 @@ class Env(Generic[ObsType, ActType]):
     """
 
     # Set this in SOME subclasses
-    metadata: dict[str, Any] = {"render_modes": {}}
+    metadata: dict[str, Any] = {"render_modes": []}
     # define render_mode if your environment supports rendering
     render_mode: str | None = None
     reward_range = (-float("inf"), float("inf"))

gymnasium/envs/box2d/bipedal_walker.py

@@ -166,7 +166,7 @@ class BipedalWalker(gym.Env, EzPickle):
     """
 
     metadata = {
-        "render_modes": {"human", "rgb_array"},
+        "render_modes": ["human", "rgb_array"],
         "render_fps": FPS,
     }
 

gymnasium/envs/box2d/car_racing.py

@@ -193,11 +193,11 @@ class CarRacing(gym.Env, EzPickle):
     """
 
     metadata = {
-        "render_modes": {
+        "render_modes": [
             "human",
             "rgb_array",
             "state_pixels",
-        },
+        ],
         "render_fps": FPS,
     }
 

gymnasium/envs/box2d/lunar_lander.py

@@ -190,7 +190,7 @@ class LunarLander(gym.Env, EzPickle):
     """
 
     metadata = {
-        "render_modes": {"human", "rgb_array"},
+        "render_modes": ["human", "rgb_array"],
         "render_fps": FPS,
     }
 

gymnasium/envs/classic_control/acrobot.py

@@ -141,7 +141,7 @@ class AcrobotEnv(Env):
     """
 
     metadata = {
-        "render_modes": {"human", "rgb_array"},
+        "render_modes": ["human", "rgb_array"],
         "render_fps": 15,
     }
 

gymnasium/envs/classic_control/cartpole.py

@@ -82,7 +82,7 @@ class CartPoleEnv(gym.Env[np.ndarray, Union[int, np.ndarray]]):
     """
 
     metadata = {
-        "render_modes": {"human", "rgb_array"},
+        "render_modes": ["human", "rgb_array"],
         "render_fps": 50,
     }
 

gymnasium/envs/classic_control/continuous_mountain_car.py

@@ -105,7 +105,7 @@ class Continuous_MountainCarEnv(gym.Env):
     """
 
     metadata = {
-        "render_modes": {"human", "rgb_array"},
+        "render_modes": ["human", "rgb_array"],
         "render_fps": 30,
     }
 

gymnasium/envs/classic_control/mountain_car.py

@@ -97,7 +97,7 @@ class MountainCarEnv(gym.Env):
     """
 
     metadata = {
-        "render_modes": {"human", "rgb_array"},
+        "render_modes": ["human", "rgb_array"],
         "render_fps": 30,
     }
 

gymnasium/envs/classic_control/pendulum.py

@@ -93,7 +93,7 @@ class PendulumEnv(gym.Env):
     """
 
     metadata = {
-        "render_modes": {"human", "rgb_array"},
+        "render_modes": ["human", "rgb_array"],
         "render_fps": 30,
     }