added rail_from_list_of_saved_GridTransitionMap_generator rail generator function

examples/temporary_example.py

@@ -23,6 +23,12 @@ env = RailEnv(width=20,
               height=20,
               rail_generator=random_rail_generator(cell_type_relative_proportion=transition_probability),
               number_of_agents=10)
+
+# env = RailEnv(width=20,
+#               height=20,
+#               rail_generator=rail_from_list_of_saved_GridTransitionMap_generator(['examples/sample_10_10_rail.npy']),
+#               number_of_agents=10)
+
 env.reset()
 
 env_renderer = RenderTool(env)

flatland/core/transition_map.py

@@ -282,7 +282,11 @@ class GridTransitionMap(TransitionMap):
             self.grid = new_grid
 
         else:
-            self.grid = self.grid * 0
+            if new_grid.dtype == np.uint16:
+                self.grid = np.zeros((self.height, self.width), dtype=np.uint16)
+            elif new_grid.dtype == np.uint64:
+                self.grid = np.zeros((self.height, self.width), dtype=np.uint64)
+
             self.grid[0:min(self.height, new_height), 0:min(self.width, new_width)] = new_grid[0:min(self.height, new_height), 0:min(self.width, new_width)]
 
 # TODO: GIACOMO: is it better to provide those methods with lists of cell_ids

flatland/envs/rail_env.py

@@ -10,7 +10,7 @@ import numpy as np
 from flatland.core.env import Environment
 from flatland.core.env_observation_builder import TreeObsForRailEnv
 
-from flatland.core.transitions import RailEnvTransitions
+from flatland.core.transitions import Grid4Transitions, Grid8Transitions, RailEnvTransitions
 from flatland.core.transition_map import GridTransitionMap
 
 
@@ -75,6 +75,33 @@ def rail_from_GridTransitionMap_generator(rail_map):
     return generator
 
 
+def rail_from_list_of_saved_GridTransitionMap_generator(list_of_filenames):
+    """
+    Utility to sequentially and cyclically return GridTransitionMap-s from a list of files, on each environment reset.
+
+    Parameters
+    -------
+    list_of_filenames : list
+        List of filenames with the saved grids to load.
+
+    Returns
+    -------
+    function
+        Generator function that always returns the given `rail_map' object.
+    """
+    def generator(width, height, num_resets=0):
+        t_utils = RailEnvTransitions()
+        rail_map = GridTransitionMap(width=width, height=height, transitions=t_utils)
+        rail_map.load_transition_map(list_of_filenames[num_resets % len(list_of_filenames)], override_gridsize=False)
+
+        if rail_map.grid.dtype == np.uint64:
+            rail_map.transitions = Grid8Transitions()
+
+        return rail_map
+
+    return generator
+
+
 """
 def generate_rail_from_list_of_manual_specifications(list_of_specifications)
     def generator(width, height, num_resets=0):