写一个使用混合蛙跳算法解决TSP问题的Python程序
时间: 2024-05-15 14:12:27 浏览: 98
以下是一个使用混合蛙跳算法(Hybrid Genetic Algorithm and Particle Swarm Optimization,HGPSO)解决TSP问题的Python程序:
```python
import numpy as np
import random
import math
# 定义TSP问题中的城市坐标
city_cords = np.array([[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]])
# 定义使用HGPSO算法解决TSP问题的类
class HGPSO_TSP:
def __init__(self, n_pop, n_city, n_iter, w=0.7, c1=1.5, c2=1.5, p_crossover=0.9, p_mutation=0.1):
self.n_pop = n_pop # 种群大小
self.n_city = n_city # 城市数量
self.n_iter = n_iter # 迭代次数
self.w = w # 惯性权重
self.c1 = c1 # 个体学习因子
self.c2 = c2 # 群体学习因子
self.p_crossover = p_crossover # 交叉概率
self.p_mutation = p_mutation # 变异概率
self.population = np.zeros((self.n_pop, self.n_city), dtype=int) # 种群中每个个体的基因型
self.fitness = np.zeros(self.n_pop) # 种群中每个个体的适应度值
self.global_best = np.zeros(self.n_city, dtype=int) # 全局最优解的基因型
self.global_best_fitness = np.inf # 全局最优解的适应度值
# 计算两个城市之间的欧氏距离
def distance(self, city1, city2):
return math.sqrt((city1[0]-city2[0])**2 + (city1[1]-city2[1])**2)
# 计算一个个体的适应度值
def evaluate(self, individual):
distance_sum = 0
for i in range(self.n_city-1):
distance_sum += self.distance(city_cords[individual[i]], city_cords[individual[i+1]])
distance_sum += self.distance(city_cords[individual[-1]], city_cords[individual[0]])
return distance_sum
# 初始化种群
def initialize_population(self):
for i in range(self.n_pop):
self.population[i] = np.random.permutation(self.n_city)
self.fitness[i] = self.evaluate(self.population[i])
# 更新全局最优解
def update_global_best(self):
for i in range(self.n_pop):
if self.fitness[i] < self.global_best_fitness:
self.global_best_fitness = self.fitness[i]
self.global_best = self.population[i]
# 选择操作
def selection(self):
fitness_sum = np.sum(1/self.fitness)
probs = (1/self.fitness) / fitness_sum
selected_indices = np.random.choice(self.n_pop, self.n_pop, p=probs)
selected_population = self.population[selected_indices]
return selected_population
# 交叉操作
def crossover(self, parent1, parent2):
child = np.zeros(self.n_city, dtype=int)
start = random.randint(0, self.n_city-1)
end = random.randint(start, self.n_city-1)
child[start:end] = parent1[start:end]
for i in range(self.n_city):
if parent2[i] not in child:
for j in range(self.n_city):
if child[j] == 0:
child[j] = parent2[i]
break
return child
# 变异操作
def mutation(self, individual):
index1 = random.randint(0, self.n_city-1)
index2 = random.randint(0, self.n_city-1)
individual[index1], individual[index2] = individual[index2], individual[index1]
return individual
# 更新种群
def update_population(self):
selected_population = self.selection()
new_population = np.zeros((self.n_pop, self.n_city), dtype=int)
for i in range(self.n_pop):
parent1 = selected_population[i]
if random.random() < self.p_crossover:
parent2 = selected_population[random.randint(0, self.n_pop-1)]
child = self.crossover(parent1, parent2)
if random.random() < self.p_mutation:
child = self.mutation(child)
new_population[i] = child
else:
new_population[i] = parent1
self.population = new_population
self.fitness = np.zeros(self.n_pop)
for i in range(self.n_pop):
self.fitness[i] = self.evaluate(self.population[i])
# 更新速度
def update_velocity(self, velocity, individual, local_best):
r1 = np.random.rand(self.n_city)
r2 = np.random.rand(self.n_city)
personal_best = individual
global_best = self.global_best
for i in range(self.n_city):
velocity[i] = self.w * velocity[i] + self.c1 * r1[i] * (personal_best[i] - individual[i]) + self.c2 * r2[i] * (global_best[i] - individual[i])
if velocity[i] > self.n_city/2:
velocity[i] = self.n_city/2
elif velocity[i] < -self.n_city/2:
velocity[i] = -self.n_city/2
return velocity
# 更新位置
def update_position(self, individual, velocity):
position = np.zeros(self.n_city, dtype=int)
temp = individual + velocity
for i in range(self.n_city):
if temp[i] > self.n_city-1:
temp[i] = self.n_city-1
elif temp[i] < 0:
temp[i] = 0
for i in range(self.n_city):
if temp[i] not in position:
position[i] = temp[i]
else:
for j in range(self.n_city):
if position[j] == 0:
position[j] = temp[i]
break
return position
# 更新局部最优解
def update_local_best(self, position, fitness):
local_best = np.zeros(self.n_city, dtype=int)
local_best_fitness = np.inf
for i in range(self.n_pop):
if fitness[i] < local_best_fitness and np.array_equal(position, self.population[i]):
local_best_fitness = fitness[i]
local_best = self.population[i]
return local_best
# HGPSO算法
def run(self):
self.initialize_population()
self.update_global_best()
velocity = np.zeros((self.n_pop, self.n_city), dtype=int)
for i in range(self.n_iter):
for j in range(self.n_pop):
velocity[j] = self.update_velocity(velocity[j], self.population[j], self.update_local_best(self.population[j], self.fitness))
self.population[j] = self.update_position(self.population[j], velocity[j])
self.fitness[j] = self.evaluate(self.population[j])
self.update_global_best()
return self.global_best, self.global_best_fitness
# 测试
n_pop = 50 # 种群大小
n_city = 20 # 城市数量
n_iter = 100 # 迭代次数
hgpso_tsp = HGPSO_TSP(n_pop, n_city, n_iter)
best_path, best_dist = hgpso_tsp.run()
print("最短路径:", best_path)
print("最短距离:", best_dist)
```
在该程序中,我们首先定义了TSP问题中的城市坐标,然后定义了一个使用HGPSO算法解决TSP问题的类`HGPSO_TSP`。在该类中,我们先定义了一个`distance`函数,用于计算两个城市之间的欧氏距离。然后,我们定义了一系列方法来实现HGPSO算法中的各个操作,包括初始化种群、计算适应度值、选择操作、交叉操作、变异操作、更新种群、更新速度、更新位置、更新局部最优解和运行算法。最后,我们设置了一些参数,调用`HGPSO_TSP`类并运行算法,输出最短路径和最短距离。
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