Calculating transitions inside Corridor env

README.md

@@ -21,8 +21,8 @@ For some usage examples look at [examples/](examples) directory.
 ## Development
 
     conda create --name openai-envs python=3.7
-    source activate openai-envs
+    conda activate openai-envs
 
-    pip install -r requirements.txt
+    pip install -e ".[testing]"
 
     python setup.py test

gym_corridor/corridor.py

@@ -15,6 +15,7 @@ class Corridor(gym.Env):
     def __init__(self, size=20):
         self._size = size
         self._position = None
+        self._transitions = self._calculate_transitions()
 
         self.observation_space = Discrete(1)
         self.action_space = Discrete(2)
@@ -47,8 +48,32 @@ def render(self, mode='human'):
         else:
             raise ValueError('Unknown visualisation mode')
 
+    def get_transitions(self):
+        return self._transitions
+
     def _visualize(self):
         corridor = ["" for _ in range(0, self._size - 1)]
         corridor[self._position - 1] = "X"
         corridor[self._size - 2] = "$"
         return "[" + ".".join(corridor) + "]"
+
+    def _calculate_transitions(self):
+        START, END = 1, self._size
+        LEFT, RIGHT = 0, 1
+
+        def _handle_state(state):
+            moves = []
+            if state == START:
+                moves.append((state, RIGHT, state + 1))
+            else:
+                moves.append((state, LEFT, state - 1))
+                moves.append((state, RIGHT, state + 1))
+
+            return moves
+
+        transitions = []
+
+        for state in range(START, END):
+            transitions += _handle_state(state)
+
+        return transitions

gym_corridor/tests/test_corridor.py

@@ -84,3 +84,13 @@ def test_should_move_in_both_directions(self):
 
         p2, _, _, _ = corr.step(MOVE_RIGHT)
         assert int(p2) == int(p0)
+
+    def test_should_calculate_transitions(self):
+        # given
+        corr = gym.make('corridor-20-v0')
+
+        # when
+        transitions = corr.env.get_transitions()
+
+        # then
+        assert len(transitions) == 37

setup.py

@@ -12,7 +12,7 @@
 ]
 
 setup(name='parrotprediction-openai-envs',
-      version='2.2.1',
+      version='2.2.2',
       description='Custom environments for OpenAI Gym',
       keywords='acs lcs machine-learning reinforcement-learning openai',
       url='https://github.com/ParrotPrediction/openai-envs',