Rename the observations variable in the evaluation util to avoid shadowing (#1288)

* Rename the observations variable in the evaluation util to avoid shadowing

This enables a callback in evaluate_policy to have access to the
observation vector that is fed to the environment step function,
which is currently shadowed by the output observation.

* Update changelog

* Add test

* Move assignment outside of the loop

---------

Co-authored-by: Antonin RAFFIN <antonin.raffin@ensta.org>
Co-authored-by: Antonin Raffin <antonin.raffin@dlr.de>

docs/misc/changelog.rst

@@ -3,6 +3,34 @@
 Changelog
 ==========
 
+Release 1.8.1a0 (WIP)
+--------------------------
+
+Breaking Changes:
+^^^^^^^^^^^^^^^^^
+- Renamed environment output observations in ``evaluate_policy`` to prevent shadowing the input observations during callbacks (@npit)
+
+New Features:
+^^^^^^^^^^^^^
+
+`SB3-Contrib`_
+^^^^^^^^^^^^^^
+
+`RL Zoo`_
+^^^^^^^^^
+
+Bug Fixes:
+^^^^^^^^^^
+
+Deprecations:
+^^^^^^^^^^^^^
+
+Others:
+^^^^^^^
+
+Documentation:
+^^^^^^^^^^^^^^
+
 
 Release 1.8.0 (2023-04-07)
 --------------------------
@@ -1271,4 +1299,4 @@ And all the contributors:
 @Gregwar @ycheng517 @quantitative-technologies @bcollazo @git-thor @TibiGG @cool-RR @MWeltevrede
 @Melanol @qgallouedec @francescoluciano @jlp-ue @burakdmb @timothe-chaumont @honglu2875 @yuanmingqi
 @anand-bala @hughperkins @sidney-tio @AlexPasqua @dominicgkerr @Akhilez @Rocamonde @tobirohrer @ZikangXiong
-@DavyMorgan @luizapozzobon @Bonifatius94 @theSquaredError @harveybellini @DavyMorgan @FieteO @jonasreiher
+@DavyMorgan @luizapozzobon @Bonifatius94 @theSquaredError @harveybellini @DavyMorgan @FieteO @jonasreiher @npit

stable_baselines3/common/evaluation.py

@@ -86,7 +86,7 @@ def evaluate_policy(
     episode_starts = np.ones((env.num_envs,), dtype=bool)
     while (episode_counts < episode_count_targets).any():
         actions, states = model.predict(observations, state=states, episode_start=episode_starts, deterministic=deterministic)
-        observations, rewards, dones, infos = env.step(actions)
+        new_observations, rewards, dones, infos = env.step(actions)
         current_rewards += rewards
         current_lengths += 1
         for i in range(n_envs):
@@ -120,6 +120,8 @@ def evaluate_policy(
                     current_rewards[i] = 0
                     current_lengths[i] = 0
 
+        observations = new_observations
+
         if render:
             env.render()
 

stable_baselines3/version.txt

@@ -1 +1 @@
-1.8.0
+1.8.1a0

tests/test_utils.py

@@ -183,6 +183,10 @@ def test_evaluate_policy(direct_policy: bool):
 
     def dummy_callback(locals_, _globals):
         locals_["model"].n_callback_calls += 1
+        assert "observations" in locals_
+        assert "new_observations" in locals_
+        assert locals_["new_observations"] is not locals_["observations"]
+        assert not np.allclose(locals_["new_observations"], locals_["observations"])
 
     assert model.policy is not None
     policy = model.policy if direct_policy else model