Merge branch '40-maljx-complex-generator-bug-fix' into 'master'

bug fix: issue 40, complex generator is returning too many agents

Closes #40

See merge request flatland/flatland!34

flatland/envs/generators.py

@@ -40,6 +40,9 @@ def complex_rail_generator(nr_start_goal=1, nr_extra=100, min_dist=20, max_dist=
     """
 
     def generator(width, height, num_agents, num_resets=0):
+        if num_agents > nr_start_goal:
+            num_agents = nr_start_goal 
+            print("complex_rail_generator: num_agents > nr_start_goal, changing num_agents")
         rail_trans = RailEnvTransitions()
         grid_map = GridTransitionMap(width=width, height=height, transitions=rail_trans)
         rail_array = grid_map.grid
@@ -49,41 +52,20 @@ def complex_rail_generator(nr_start_goal=1, nr_extra=100, min_dist=20, max_dist=
 
         # generate rail array
         # step 1:
-        # - generate a list of start and goal positions
-        # - use a min/max distance allowed as input for this
-        # - validate that start/goals are not placed too close to other start/goals
-        #
-        # step 2: (optional)
-        # - place random elements on rails array
-        #   - for instance "train station", etc.
-        #
-        # step 3:
-        # - iterate over all [start, goal] pairs:
-        #   - [first X pairs]
-        #     - draw a rail from [start,goal]
-        #     - draw either vertical or horizontal part first (randomly)
+        # - generate a start and goal position
+        #   - validate min/max distance allowed
+        #   - validate that start/goals are not placed too close to other start/goals
+        #   - draw a rail from [start,goal]
         #     - if rail crosses existing rail then validate new connection
-        #       - if new connection is invalid turn 90 degrees to left/right
-        #       - possibility that this fails to create a path to goal
-        #         - on failure goto step1 and retry with seed+1
-        #     - [avoid crossing other start,goal positions] (optional)
+        #     - possibility that this fails to create a path to goal
+        #     - on failure generate new start/goal
         #
-        #   - [after X pairs]
-        #     - find closest rail from start (Pa)
-        #       - iterating outwards in a "circle" from start until an existing rail cell is hit
-        #     - connect [start, Pa]
-        #       - validate crossing rails
-        #     - Do A* from Pa to find closest point on rail (Pb) to goal point
-        #       - Basically normal A* but find point on rail which is closest to goal
-        #       - since full path to goal is unlikely
-        #     - connect [Pb, goal]
-        #       - validate crossing rails
+        # step 2:
+        # - add more rails to map randomly between cells that have rails
+        #   - validate all new rails, on failure don't add new rails
         #
-        # step 4: (optional)
-        # - add more rails to map randomly
-        #
-        # step 5:
-        # - return transition map + list of [start, goal] points
+        # step 3:
+        # - return transition map + list of [start_pos, start_dir, goal_pos] points
         #
 
         start_goal = []
@@ -161,9 +143,9 @@ def complex_rail_generator(nr_start_goal=1, nr_extra=100, min_dist=20, max_dist=
         # print("\n> Complex Rail Gen: Created #", len(start_goal), "pairs and #", nr_created, "extra connections")
         # print(start_goal)
 
-        agents_position = [sg[0] for sg in start_goal]
-        agents_target = [sg[1] for sg in start_goal]
-        agents_direction = start_dir
+        agents_position = [sg[0] for sg in start_goal[:num_agents]]
+        agents_target = [sg[1] for sg in start_goal[:num_agents]]
+        agents_direction = start_dir[:num_agents]
 
         return grid_map, agents_position, agents_direction, agents_target