Merge pull request #508 from dvstter/steganography

fix #506

Author: kengz

README.md

@@ -9,6 +9,7 @@
   <br><br>
 </p>
 
+>NOTE: the `book` branch has been updated for issue fixes. For the original code in the book _Foundations of Deep Reinforcement Learning_, check out to git tag `v4.1.1`
 
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 |:---:|:---:|:---:|:---:|

slm_lab/env/base.py

@@ -142,6 +142,8 @@ def _get_spaces(self, u_env):
     def _get_observable_dim(self, observation_space):
         '''Get the observable dim for an agent in env'''
         state_dim = observation_space.shape
+        if isinstance(observation_space, spaces.MultiDiscrete):
+            state_dim = observation_space.nvec.tolist()
         if len(state_dim) == 1:
             state_dim = state_dim[0]
         return {'state': state_dim}