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maze.py
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maze.py
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import sys
from PIL import Image, ImageDraw
import time
class Node():
def __init__(self, state, parent, action):
self.state = state
self.parent = parent
self.action = action
class StackFrontier():
def __init__(self):
self.frontier = []
def add(self, node):
self.frontier.append(node)
def contains_state(self, state):
return any(node.state == state for node in self.frontier)
def empty(self):
return len(self.frontier) == 0
def remove(self):
if self.empty():
raise Exception("empty frontier")
else:
node = self.frontier[-1]
self.frontier = self.frontier[:-1]
return node
class QueueFrontier(StackFrontier):
def remove(self):
if self.empty():
raise Exception("empty frontier")
else:
node = self.frontier[0]
self.frontier = self.frontier[1:]
return node
class Maze():
def __init__(self, filename):
# set height and width of maze from Maze.txt
with open(filename) as f:
contents = f.read()
# Validate start and goal
if contents.count("A") != 1:
raise Exception("Maze must have one Start Point")
if contents.count("B") != 1:
raise Exception("Maze must have one End Point")
# Determine height and width of maze
contents = contents.splitlines()
self.height = len(contents)
self.width = max(len(line) for line in contents)
# Keep track of walls
self.walls = []
for i in range(self.height):
row = []
for j in range(self.width):
try:
if contents[i][j] == "A":
self.start = (i, j)
row.append(False)
elif contents[i][j] == "B":
self.goal = (i, j)
row.append(False)
elif contents[i][j] == " ":
row.append(False)
else:
row.append(True)
except IndexError:
row.append(False)
self.walls.append(row)
self.solution = None
def print(self):
solution = self.solution[1] if self.solution is not None else None
print()
for i, row in enumerate(self.walls):
for j, col in enumerate(row):
if col:
print("█", end="")
elif (i, j) == self.start:
print("A", end="")
elif (i, j) == self.goal:
print("B", end="")
elif solution is not None and (i, j) in solution:
print(".", end="")
else:
print(" ", end="")
print()
print()
def neighbors(self, state):
row, col = state
candidates = [
("up", (row - 1, col)),
("down", (row + 1, col)),
("left", (row, col - 1)),
("right", (row, col + 1))
]
result = []
for action, (r, c) in candidates:
if 0 <= r < self.height and 0 <= c < self.width and not self.walls[r][c]:
result.append((action, (r, c)))
return result
def solve(self):
# number of states explored
self.num_explored = 0
# Initialize frontier to the starting position
start = Node(state=self.start, parent=None, action=None)
frontier = StackFrontier()
frontier.add(start)
# Initialize empty explored set
self.explored = set()
# Loop until solve
while True:
# nothing left in frontier = no path
if frontier.empty():
raise Exception("no solution")
# Choose node from the frontier
node = frontier.remove()
self.num_explored += 1
# Node goal = solution
if node.state == self.goal:
actions = []
cells = []
while node.parent is not None:
actions.append(node.action)
cells.append(node.state)
node = node.parent
actions.reverse()
cells.reverse()
self.solution = (actions, cells)
return
# Mark node as explored
self.explored.add(node.state)
# Add neighbors to frontier
for action, state in self.neighbors(node.state):
if not frontier.contains_state(state) and state not in self.explored:
child = Node(state=state, parent=node, action=action)
frontier.add(child)
#creating the Img
def output_image(self, filename, show_solution=True, show_explored=False):
cell_size = 50
cell_border = 2
# Create a blank canvas
img = Image.new(
"RGBA",
(self.width * cell_size, self.height * cell_size),
"black"
)
draw = ImageDraw.Draw(img)
solution = self.solution[1] if self.solution is not None else None
for i, row in enumerate(self.walls):
for j, col in enumerate(row):
# Walls
if col:
fill = (40, 40, 40)
# Start
elif (i, j) == self.start:
fill = (255, 0, 0)
# Goal
elif (i, j) == self.goal:
fill = (0, 171, 28)
# Solution
elif solution is not None and show_solution and (i, j) in solution:
fill = (220, 235, 113)
# Explored
elif solution is not None and show_explored and (i, j) in self.explored:
fill = (212, 97, 85)
# Empty cell
else:
fill = (237, 240, 252)
# Draw cell
draw.rectangle(
([(j * cell_size + cell_border, i * cell_size + cell_border),
((j + 1) * cell_size - cell_border, (i + 1) * cell_size - cell_border)]),
fill=fill
)
img.save(filename)
# run the program
if len(sys.argv) != 2:
sys.exit("Usage: python3 maze.py maze.txt")
#printing the maze
m = Maze(sys.argv[1])
print("Maze:")
m.print()
print("Solving...")
m.solve()
# Solved Maze
print("States Explored:", m.num_explored)
print("Solution:")
m.print()
# Image of solved Maze
m.output_image("maze.png", show_explored=True)
image = Image.open('maze.png')
image.show()