双向A算法是一种常用的路径规划算法,如何实现任意起点和终点的双向A算法呢?这里提供一种参考实现:
def any_goal_bidirectional_A_star(start, goals, heuristic_func, neighbor_func, distance_func): # 初始化起点和终点列表 start_to_goals = {goal: [start, float('inf')] for goal in goals} goal_to_starts = {start: [goal, float('inf')] for goal in goals}
# 初始化搜索队列和已经访问过的点集
forward_queue = PriorityQueue()
backward_queue = PriorityQueue()
forward_closed = set()
backward_closed = set()
# 将起点和终点添加到搜索队列中
forward_queue.put(start_to_goals[goals[0]], start_to_goals[goals[0]][1] + heuristic_func(start, goals[0]))
backward_queue.put(goal_to_starts[goals[0]], goal_to_starts[goals[0]][1] + heuristic_func(start, goals[0]))
while not forward_queue.empty() and not backward_queue.empty():
# 前向搜索一步
forward_node, forward_f_value = forward_queue.get()
forward_curr, forward_dist = forward_node
forward_closed.add(forward_curr)
# 找到与前向搜索相同的点
back_node, back_f_value = goal_to_starts.get(forward_curr, [None, float('inf')])
if back_node is not None:
# 找到路径
path = [forward_node[0]]
while forward_curr != start:
path.append(start_to_goals[forward_curr][0])
forward_curr = start_to_goals[forward_curr][0]
path = list(reversed(path))
while back_node[0] != start:
path.append(back_node[0])
back_node = goal_to_starts[back_node[0]]
return path
# 扩展前向搜索节点
for neighbor in neighbor_func(forward_curr):
if neighbor in forward_closed:
continue
new_dist = forward_dist + distance_func(forward_curr, neighbor)