mirror of
https://github.com/zhm-real/PathPlanning.git
synced 2026-08-30 00:50:46 +08:00
zhm-real
82 lines
2.7 KiB
Python
82 lines
2.7 KiB
Python
#!/usr/bin/env python3
|
|
# -*- coding: utf-8 -*-
|
|
"""
|
|
@author: huiming zhou
|
|
"""
|
|
|
|
import queue
|
|
import plotting
|
|
import env
|
|
|
|
|
|
class BFS:
|
|
def __init__(self, x_start, x_goal):
|
|
self.xI, self.xG = x_start, x_goal
|
|
|
|
self.Env = env.Env()
|
|
self.u_set = self.Env.motions # feasible input set
|
|
self.obs = self.Env.obs # position of obstacles
|
|
[self.path, self.policy, self.visited] = self.searching(self.xI, self.xG)
|
|
|
|
self.fig_name = "Breadth-first Searching"
|
|
plotting.animation(self.xI, self.xG, self.obs,
|
|
self.path, self.visited, self.fig_name) # animation generate
|
|
|
|
|
|
def searching(self, xI, xG):
|
|
"""
|
|
Searching using BFS.
|
|
|
|
:return: planning path, action in each node, visited nodes in the planning process
|
|
"""
|
|
|
|
q_bfs = queue.QueueFIFO() # first-in-first-out queue
|
|
q_bfs.put(xI)
|
|
parent = {xI: xI} # record parents of nodes
|
|
action = {xI: (0, 0)} # record actions of nodes
|
|
visited = []
|
|
|
|
while not q_bfs.empty():
|
|
x_current = q_bfs.get()
|
|
if x_current == xG:
|
|
break
|
|
visited.append(x_current)
|
|
for u_next in self.u_set: # explore neighborhoods of current node
|
|
x_next = tuple([x_current[i] + u_next[i] for i in range(len(x_current))])
|
|
if x_next not in parent and x_next not in self.obs: # node not visited and not in obstacles
|
|
q_bfs.put(x_next)
|
|
parent[x_next], action[x_next] = x_current, u_next
|
|
|
|
[path, policy] = self.extract_path(xI, xG, parent, action) # extract path
|
|
|
|
return path, policy, visited
|
|
|
|
|
|
def extract_path(self, xI, xG, parent, policy):
|
|
"""
|
|
Extract the path based on the relationship of nodes.
|
|
|
|
:param xI: Starting node
|
|
:param xG: Goal node
|
|
:param parent: Relationship between nodes
|
|
:param policy: Action needed for transfer between two nodes
|
|
:return: The planning path
|
|
"""
|
|
|
|
path_back = [xG]
|
|
acts_back = [policy[xG]]
|
|
x_current = xG
|
|
while True:
|
|
x_current = parent[x_current]
|
|
path_back.append(x_current)
|
|
acts_back.append(policy[x_current])
|
|
if x_current == xI: break
|
|
|
|
return list(path_back), list(acts_back)
|
|
|
|
|
|
if __name__ == '__main__':
|
|
x_Start = (5, 5) # Starting node
|
|
x_Goal = (49, 5) # Goal node
|
|
bfs = BFS(x_Start, x_Goal)
|