Create environment.py

Author: mpwusr

environment.py

@@ -0,0 +1,89 @@
+import numpy as np
+
+ACTIONS = {'U': (-1, 0), 'D': (1, 0), 'L': (0, -1), 'R': (0, 1)}
+
+class Maze(object):
+    def __init__(self):
+        self.maze = np.zeros((6, 6))
+        self.maze[0, 0] = 2
+        self.maze[5, :5] = 1
+        self.maze[:4, 5] = 1
+        self.maze[2, 2:] = 1
+        self.maze[3, 2] = 1
+        self.robot_position = (0, 0)
+        self.steps = 0
+        self.construct_allowed_states()
+
+    def print_maze(self):
+        print('---------------------------------')
+        for row in self.maze:
+            for col in row:
+                if col == 0:
+                    print('', end="\t") # empty space
+                elif col == 1:
+                    print('X', end="\t") # walls
+                elif col == 2:
+                    print('R', end="\t") # robot position
+            print("\n")
+        print('---------------------------------')
+
+    def is_allowed_move(self, state, action):
+        # check allowed move from a given state
+        y, x = state
+        y += ACTIONS[action][0]
+        x += ACTIONS[action][1]
+        if y < 0 or x < 0 or y > 5 or x > 5:
+            # if robot will move off the board
+            return False
+
+        if self.maze[y, x] == 0 or self.maze[y, x] == 2:
+            # if robot moves into empty space or its original start position
+            return True
+        else:
+            return False
+
+    def construct_allowed_states(self):
+        # create a dictionary of allowed states from any position
+        # using the isAllowedMove() function
+        # this is so that you don't have to call the function every time
+        allowed_states = {}
+        for y, row in enumerate(self.maze):
+            for x, col in enumerate(row):
+                # iterate through all spaces
+                if self.maze[(y,x)] != 1:
+                    # if the space is not a wall, add it to the allowed states dictionary
+                    allowed_states[(y,x)] = []
+                    for action in ACTIONS:
+                        if self.is_allowed_move((y,x), action) & (action != 0):
+                            allowed_states[(y,x)].append(action)
+        self.allowed_states = allowed_states
+
+    def update_maze(self, action):
+        y, x = self.robot_position # get current position
+        self.maze[y, x] = 0 # set the current position to 0
+        y += ACTIONS[action][0] # get new position
+        x += ACTIONS[action][1] # get new position
+        self.robot_position = (y, x) # set new position
+        self.maze[y, x] = 2 # set new position
+        self.steps += 1 # add steps
+
+    def is_game_over(self):
+        # check if robot in the final position
+        if self.robot_position == (5, 5):
+            return True
+        else:
+            return False
+
+    def get_state_and_reward(self):
+        return self.robot_position, self.give_reward()
+
+    def give_reward(self):
+        # if at end give 0 reward
+        # if not at end give -1 reward
+        if self.robot_position == (5, 5):
+            return 0
+        else:
+            return -1
+
+    def get_robot_position(self):
+        return self.robot_position