Changed state from list to tuple (aimacode#603)

Chipe1 · norvig · commit 2a20e0429365 · 2017-08-06T23:10:04.000-07:00
diff --git a/probability.py b/probability.py
@@ -661,14 +661,14 @@ def __init__(self, m):
         self.nrows = len(m)
         self.ncols = len(m[0])
         # list of empty spaces in the map
-        self.empty = [[i, j] for i in range(self.nrows) for j in range(self.ncols) if not m[i][j]]
+        self.empty = [(i, j) for i in range(self.nrows) for j in range(self.ncols) if not m[i][j]]
 
     def sample(self):
         """Returns a random kinematic state possible in the map"""
         pos = random.choice(self.empty)
         # 0N 1E 2S 3W
         orient = random.choice(range(4))
-        kin_state = pos + [orient]
+        kin_state = pos + (orient,)
         return kin_state
 
     def ray_cast(self, sensor_num, kin_state):
@@ -679,10 +679,10 @@ def ray_cast(self, sensor_num, kin_state):
         #  0
         # 3R1
         #  2
-        delta = [(sensor_num%2 == 0)*(sensor_num - 1), (sensor_num%2 == 1)*(2 - sensor_num)]
+        delta = ((sensor_num%2 == 0)*(sensor_num - 1), (sensor_num%2 == 1)*(2 - sensor_num))
         # sensor direction changes based on orientation
         for _ in range(orient):
-            delta = [delta[1], -delta[0]]
+            delta = (delta[1], -delta[0])
         range_count = 0
         while (0 <= pos[0] < self.nrows) and (0 <= pos[1] < self.nrows) and (not self.m[pos[0]][pos[1]]):
             pos = vector_add(pos, delta)
diff --git a/tests/test_probability.py b/tests/test_probability.py
@@ -192,9 +192,9 @@ def P_motion_sample(kin_state, v, w):
         # for simplicity the robot first rotates and then moves
         orient = (orient + w)%4
         for _ in range(orient):
-            v = [v[1], -v[0]]
-        pos = list(vector_add(pos, v))
-        return pos + [orient]
+            v = (v[1], -v[0])
+        pos = vector_add(pos, v)
+        return pos + (orient,)
 
     def P_sensor(x, y):
         """Conditional probability for sensor reading"""
@@ -207,8 +207,8 @@ def P_sensor(x, y):
             return 0
 
     from utils import print_table
-    a = {'v': [0, 0], 'w': 0}
-    z = [2, 4, 1, 6]
+    a = {'v': (0, 0), 'w': 0}
+    z = (2, 4, 1, 6)
     S = monte_carlo_localization(a, z, 1000, P_motion_sample, P_sensor, m)
     grid = [[0]*17 for _ in range(11)]
     for x, y, _ in S:
@@ -217,8 +217,8 @@ def P_sensor(x, y):
     print("GRID:")
     print_table(grid)
 
-    a = {'v': [0, 1], 'w': 0}
-    z = [2, 3, 5, 7]
+    a = {'v': (0, 1), 'w': 0}
+    z = (2, 3, 5, 7)
     S = monte_carlo_localization(a, z, 1000, P_motion_sample, P_sensor, m, S)
     grid = [[0]*17 for _ in range(11)]
     for x, y, _ in S:
