From a043711c10fc564e950e34ff1c45b1f8f06a57d6 Mon Sep 17 00:00:00 2001
From: maxhuettenrauch <max.huettenrauch@gmail.com>
Date: Thu, 18 Apr 2024 16:16:57 +0200
Subject: [PATCH] Fix/deterministic action space sampling in SubprocVectorEnv
 (#1103)

---
 test/base/test_action_space_sampling.py | 57 +++++++++++++++++++++++++
 tianshou/env/worker/subproc.py          |  1 +
 2 files changed, 58 insertions(+)
 create mode 100644 test/base/test_action_space_sampling.py

diff --git a/test/base/test_action_space_sampling.py b/test/base/test_action_space_sampling.py
new file mode 100644
index 0000000..fbbf25c
--- /dev/null
+++ b/test/base/test_action_space_sampling.py
@@ -0,0 +1,57 @@
+import gymnasium as gym
+
+from tianshou.env import DummyVectorEnv, ShmemVectorEnv, SubprocVectorEnv
+
+
+def test_gym_env_action_space() -> None:
+    env = gym.make("Pendulum-v1")
+    env.action_space.seed(0)
+    action1 = env.action_space.sample()
+
+    env.action_space.seed(0)
+    action2 = env.action_space.sample()
+
+    assert action1 == action2
+
+
+def test_dummy_vec_env_action_space() -> None:
+    num_envs = 4
+    envs = DummyVectorEnv([lambda: gym.make("Pendulum-v1") for _ in range(num_envs)])
+    envs.seed(0)
+    action1 = [ac_space.sample() for ac_space in envs.action_space]
+
+    envs.seed(0)
+    action2 = [ac_space.sample() for ac_space in envs.action_space]
+
+    assert action1 == action2
+
+
+def test_subproc_vec_env_action_space() -> None:
+    num_envs = 4
+    envs = SubprocVectorEnv([lambda: gym.make("Pendulum-v1") for _ in range(num_envs)])
+    envs.seed(0)
+    action1 = [ac_space.sample() for ac_space in envs.action_space]
+
+    envs.seed(0)
+    action2 = [ac_space.sample() for ac_space in envs.action_space]
+
+    assert action1 == action2
+
+
+def test_shmem_vec_env_action_space() -> None:
+    num_envs = 4
+    envs = ShmemVectorEnv([lambda: gym.make("Pendulum-v1") for _ in range(num_envs)])
+    envs.seed(0)
+    action1 = [ac_space.sample() for ac_space in envs.action_space]
+
+    envs.seed(0)
+    action2 = [ac_space.sample() for ac_space in envs.action_space]
+
+    assert action1 == action2
+
+
+if __name__ == "__main__":
+    test_gym_env_action_space()
+    test_dummy_vec_env_action_space()
+    test_subproc_vec_env_action_space()
+    test_shmem_vec_env_action_space()
diff --git a/tianshou/env/worker/subproc.py b/tianshou/env/worker/subproc.py
index ab84ac0..2637df4 100644
--- a/tianshou/env/worker/subproc.py
+++ b/tianshou/env/worker/subproc.py
@@ -126,6 +126,7 @@ def _worker(
                 if hasattr(env, "seed"):
                     p.send(env.seed(data))
                 else:
+                    env.action_space.seed(seed=data)
                     env.reset(seed=data)
                     p.send(None)
             elif cmd == "getattr":