included warning message if predictor or observation builder does not provide cells to render.

examples/training_example.py

@@ -84,7 +84,7 @@ for trials in range(1, n_trials + 1):
         # Environment step which returns the observations for all agents, their corresponding
         # reward and whether their are done
         next_obs, all_rewards, done, _ = env.step(action_dict)
-        env_renderer.render_env(show=True, show_observations=False, show_predictions=True)
+        env_renderer.render_env(show=True, show_observations=True, show_predictions=True)
 
         # Update replay buffer and train agent
         for a in range(env.get_num_agents()):

flatland/envs/predictions.py

@@ -163,7 +163,7 @@ class ShortestPathPredictorForRailEnv(PredictionBuilder):
                 # prediction is ready
                 prediction[index] = [index, *new_position, new_direction, 0]
                 visited.add((new_position[0], new_position[1], new_direction))
-            # self.env.dev_pred_dict[agent.handle] = visited
+            self.env.dev_pred_dict[agent.handle] = visited
             prediction_dict[agent.handle] = prediction
 
             # cleanup: reset initial position

flatland/utils/rendertools.py

@@ -280,7 +280,9 @@ class RenderTool(object):
 
         # Check if the observation builder provides an observation
         if len(observation_dict) < 1:
-            warnings.warn("Observation Builder did not provide an observation_dict of all observed cells.")
+            warnings.warn(
+                "Predictor did not provide any predicted cells to render. \
+                Observaiton builder needs to populate: env.dev_obs_dict")
         else:
             for agent in agent_handles:
                 color = self.gl.get_agent_color(agent)
@@ -299,7 +301,13 @@ class RenderTool(object):
         """
         rt = self.__class__
         if len(prediction_dict) < 1:
-            warnings.warn("Predictor did not provide any predicted cells to render.")
+            warnings.warn(
+                "Predictor did not provide any predicted cells to render. \
+                Predictors builder needs to populate: env.dev_pred_dict")
+
+
+
+
         else:
             for agent in agent_handles:
                 color = self.gl.get_agent_color(agent)