Added example reward functions.

reward-example-follow-centre-line.py

@@ -0,0 +1,25 @@
+def reward_function(params):
+    '''
+    Example of rewarding the agent to follow center line
+    '''
+    
+    # Read input parameters
+    track_width = params['track_width']
+    distance_from_center = params['distance_from_center']
+
+    # Calculate 3 markers that are increasingly further away from the center line
+    marker_1 = 0.1 * track_width
+    marker_2 = 0.25 * track_width
+    marker_3 = 0.5 * track_width
+
+    # Give higher reward if the car is closer to center line and vice versa
+    if distance_from_center <= marker_1:
+        reward = 1
+    elif distance_from_center <= marker_2:
+        reward = 0.5
+    elif distance_from_center <= marker_3:
+        reward = 0.1
+    else:
+        reward = 1e-3  # likely crashed/ close to off track
+
+    return reward