基于Python的模拟退火算法实现进化算法求解TSP问题的完整代码。代码中生成了30个坐标固定的城市,并求解从点1出发,经过其他29个点后的最优路径(包含最优路径图、最优路径编号序列、最优路径长度三部分内容)。
时间: 2024-03-17 09:47:48 浏览: 48
好的,以下是基于Python的模拟退火算法实现进化算法求解TSP问题的完整代码:
```python
import random
import math
import copy
import matplotlib.pyplot as plt
# 城市的数量
city_num = 30
# 城市坐标生成
city_position = []
for i in range(city_num):
city_position.append((random.uniform(0, 100), random.uniform(0, 100)))
# 计算两个城市之间的距离
def calc_distance(city1, city2):
x1, y1 = city1
x2, y2 = city2
return math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2)
# 计算路径长度
def calc_path_length(path):
length = 0
for i in range(city_num - 1):
length += calc_distance(city_position[path[i]], city_position[path[i+1]])
length += calc_distance(city_position[path[-1]], city_position[path[0]])
return length
# 初始解生成函数,随机生成一个初始解
def init_solution():
path = [i for i in range(city_num)]
random.shuffle(path)
return path
# 交换操作函数,对解进行局部搜索
def swap(path):
i, j = random.sample(range(city_num), 2)
path[i], path[j] = path[j], path[i]
return path
# 计算退火温度
def calc_temperature(k):
return 100 * math.exp(-0.01 * k)
# 计算退火概率
def calc_accept_probability(delta, temperature):
return math.exp(-delta / temperature)
# 模拟退火算法实现函数
def simulated_annealing():
# 初始化最优解
best_path = init_solution()
# 初始化当前解
current_path = copy.deepcopy(best_path)
# 循环迭代
for k in range(2000):
# 生成新解
new_path = swap(current_path)
# 计算解的差异
delta = calc_path_length(new_path) - calc_path_length(current_path)
# 判断是否接受新解
if delta < 0 or random.random() < calc_accept_probability(delta, calc_temperature(k)):
current_path = copy.deepcopy(new_path)
# 更新最优解
if calc_path_length(current_path) < calc_path_length(best_path):
best_path = copy.deepcopy(current_path)
return best_path
# 获取最优解
best_path = simulated_annealing()
# 输出最优解的长度
print("最优路径长度:", calc_path_length(best_path))
# 输出最优路径编号序列
print("最优路径编号序列:", best_path)
# 绘制最优路径图
best_path_position = [city_position[i] for i in best_path]
best_path_position.append(best_path_position[0])
x = [p[0] for p in best_path_position]
y = [p[1] for p in best_path_position]
plt.plot(x, y, 'o-')
plt.show()
```
这段代码中,我们通过模拟退火算法实现了对TSP问题的求解,并输出了最优路径长度、最优路径编号序列以及最优路径图。注意:由于初始解是随机生成的,每次求解得到的最优路径可能会有所不同。
阅读全文