120 lines
3.5 KiB
Python
120 lines
3.5 KiB
Python
class Node:
|
|
"""A node class for A* Pathfinding"""
|
|
|
|
def __init__(self, parent=None, position=None):
|
|
self.parent = parent
|
|
self.position = position
|
|
|
|
self.g = 0
|
|
self.h = 0
|
|
self.f = 0
|
|
|
|
def __eq__(self, other):
|
|
return self.position == other.position
|
|
|
|
|
|
def astar(maze, start, end):
|
|
"""Returns a list of tuples as a path from the given start to the given end in the given maze"""
|
|
|
|
# Create start and end node
|
|
start_node = Node(None, start)
|
|
start_node.g = start_node.h = start_node.f = 0
|
|
end_node = Node(None, end)
|
|
end_node.g = end_node.h = end_node.f = 0
|
|
|
|
# Initialize both open and closed list
|
|
open_list = []
|
|
closed_list = []
|
|
|
|
# Add the start node
|
|
open_list.append(start_node)
|
|
|
|
# Loop until you find the end
|
|
while len(open_list) > 0:
|
|
|
|
# Get the current node
|
|
current_node = open_list[0]
|
|
current_index = 0
|
|
for index, item in enumerate(open_list):
|
|
if item.f < current_node.f:
|
|
current_node = item
|
|
current_index = index
|
|
|
|
# Pop current off open list, add to closed list
|
|
open_list.pop(current_index)
|
|
closed_list.append(current_node)
|
|
|
|
# Found the goal
|
|
if current_node == end_node:
|
|
path = []
|
|
current = current_node
|
|
while current is not None:
|
|
path.append(current.position)
|
|
current = current.parent
|
|
return path[::-1] # Return reversed path
|
|
|
|
# Generate children
|
|
children = []
|
|
for new_position in [(0, -1), (0, 1), (-1, 0), (1, 0)]: # Adjacent squares
|
|
|
|
# Get node position
|
|
node_position = (current_node.position[0] + new_position[0], current_node.position[1] + new_position[1])
|
|
|
|
# Make sure within range
|
|
if node_position[0] > (len(maze) - 1) or node_position[0] < 0 or node_position[1] > (len(maze[len(maze)-1]) -1) or node_position[1] < 0:
|
|
continue
|
|
|
|
# Make sure walkable terrain
|
|
if maze[node_position[0]][node_position[1]] != 0:
|
|
continue
|
|
|
|
# Create new node
|
|
new_node = Node(current_node, node_position)
|
|
|
|
# Append
|
|
children.append(new_node)
|
|
|
|
# Loop through children
|
|
for child in children:
|
|
|
|
# Child is on the closed list
|
|
for closed_child in closed_list:
|
|
if child == closed_child:
|
|
continue
|
|
|
|
# Create the f, g, and h values
|
|
child.g = current_node.g + 1
|
|
child.h = ((child.position[0] - end_node.position[0]) ** 2) + ((child.position[1] - end_node.position[1]) ** 2)
|
|
child.f = child.g + child.h
|
|
|
|
# Child is already in the open list
|
|
for open_node in open_list:
|
|
if child == open_node and child.g > open_node.g:
|
|
continue
|
|
|
|
# Add the child to the open list
|
|
open_list.append(child)
|
|
|
|
|
|
def main():
|
|
|
|
maze = [[0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
|
|
[0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
|
|
[0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
|
|
[0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
|
|
[0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
|
|
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
|
|
[0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
|
|
[0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
|
|
[0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
|
|
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
|
|
|
|
start = (0, 0)
|
|
end = (7, 6)
|
|
|
|
path = astar(maze, start, end)
|
|
print(path)
|
|
|
|
|
|
if __name__ == '__main__':
|
|
main() |