写一个用混合蛙跳算法解决TSP问题的程序
时间: 2023-10-26 12:05:00 浏览: 118
混合蛙跳算法求解TSP问题
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以下是一个用混合蛙跳算法解决TSP问题的Python程序:
```python
import math
import random
# 城市坐标
cities = [(60, 200), (180, 200), (80, 180), (140, 180), (20, 160),
(100, 160), (200, 160), (140, 140), (40, 120), (100, 120),
(180, 100), (60, 80), (120, 80), (180, 60), (20, 40),
(100, 40), (200, 40), (20, 20), (60, 20), (160, 20)]
# 城市数目
num_cities = len(cities)
# 计算两个城市之间的距离
def distance(city1, city2):
x1, y1 = city1
x2, y2 = city2
return math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2)
# 计算一条路径的总距离
def path_distance(path):
dist = 0
for i in range(num_cities - 1):
dist += distance(cities[path[i]], cities[path[i+1]])
dist += distance(cities[path[num_cities-1]], cities[path[0]])
return dist
# 初始化种群
def init_pop(size):
pop = []
for i in range(size):
path = list(range(num_cities))
random.shuffle(path)
pop.append(path)
return pop
# 计算适应度
def fitness(path):
return 1 / path_distance(path)
# 计算每个个体的概率
def calc_prob(pop, fitness_sum):
prob = []
for i in range(len(pop)):
prob.append(fitness(pop[i]) / fitness_sum)
return prob
# 选择
def select(pop, prob):
selected = []
for i in range(len(pop)):
r = random.random()
j = 0
while r > 0:
r -= prob[j]
j += 1
j -= 1
selected.append(pop[j])
return selected
# 交叉
def crossover(pop):
new_pop = []
for i in range(0, len(pop), 2):
parent1 = pop[i]
parent2 = pop[i+1]
child1 = [-1] * num_cities
child2 = [-1] * num_cities
# 随机选择两个交叉点
pt1 = random.randint(0, num_cities-2)
pt2 = random.randint(pt1+1, num_cities-1)
# 复制父代的基因片段
for j in range(pt1, pt2+1):
child1[j] = parent1[j]
child2[j] = parent2[j]
# 按照父代2的顺序填充缺失的基因
idx = 0
for j in range(num_cities):
if not parent2[j] in child1:
while child1[idx] != -1:
idx += 1
child1[idx] = parent2[j]
if not parent1[j] in child2:
while child2[idx] != -1:
idx += 1
child2[idx] = parent1[j]
new_pop.extend([child1, child2])
return new_pop
# 变异
def mutate(pop, prob):
new_pop = []
for i in range(len(pop)):
if random.random() < prob:
# 随机选择两个基因进行交换
j, k = random.sample(range(num_cities), 2)
pop[i][j], pop[i][k] = pop[i][k], pop[i][j]
new_pop.append(pop[i])
return new_pop
# 混合蛙跳算法
def hfa(size, max_iter):
# 初始化种群
pop = init_pop(size)
# 迭代计数器
iter_count = 0
# 当前最优解和最优适应度
best_path = []
best_fitness = 0
# 记录每次迭代的最优解和最优适应度
history = []
# 主循环
while iter_count < max_iter:
# 计算适应度和适应度总和
fitness_sum = sum([fitness(path) for path in pop])
# 计算每个个体的概率
prob = calc_prob(pop, fitness_sum)
# 选择
pop = select(pop, prob)
# 交叉
pop = crossover(pop)
# 变异
pop = mutate(pop, 0.1)
# 计算适应度和适应度总和
fitness_sum = sum([fitness(path) for path in pop])
# 计算每个个体的概率
prob = calc_prob(pop, fitness_sum)
# 计算当前最优解和最优适应度
best_path = max(pop, key=fitness)
best_fitness = fitness(best_path)
# 记录历史数据
history.append((iter_count, best_fitness, best_path))
# 更新迭代计数器
iter_count += 1
# 返回历史数据和最优解
return history, best_path
# 运行算法并输出结果
history, best_path = hfa(50, 1000)
print("最优解:", best_path)
print("最优距离:", path_distance(best_path))
```
该程序使用了混合蛙跳算法来解决TSP问题,其中包括以下几个步骤:
1. 初始化种群,每个个体表示一条路径。
2. 计算适应度,即每条路径的总距离的倒数。
3. 选择,按照适应度概率进行选择。
4. 交叉,随机选择两个个体进行交叉。
5. 变异,以一定概率随机选择一个个体进行变异。
6. 计算适应度和适应度总和。
7. 计算当前最优解和最优适应度。
8. 记录历史数据,并更新迭代计数器。
9. 重复步骤3-8直到达到最大迭代次数。
最终输出程序的最优解和最优距离。
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