用python脚本实现:遗传平衡和遗传漂变的计算机模拟:每个群体的大小分别选取10,20,50,100,1000,10000;遗传的代数分别选取1,2,3,5,10,50,100,500,1000
时间: 2024-06-13 08:08:28 浏览: 143
以下是实现遗传平衡和遗传漂变的Python脚本,其中包括了不同群体大小和遗传代数的计算机模拟:
```python
import random
# 定义一个个体类
class Individual:
def __init__(self, chromosome):
self.chromosome = chromosome
self.fitness = self.calculate_fitness()
# 计算适应度函数
def calculate_fitness(self):
fitness = 0
for i in range(len(self.chromosome) - 1):
fitness += distance[self.chromosome[i]][self.chromosome[i+1]]
fitness += distance[self.chromosome[-1]][self.chromosome[0]]
return fitness
# 定义一个种群类
class Population:
def __init__(self, size):
self.size = size
self.population = []
for i in range(size):
chromosome = list(range(num_cities))
random.shuffle(chromosome)
individual = Individual(chromosome)
self.population.append(individual)
# 选择操作
def selection(self):
parents = []
for i in range(2):
candidates = random.sample(self.population, 5)
candidates = sorted(candidates, key=lambda x: x.fitness)
parents.append(candidates[0])
return parents
# 交叉操作
def crossover(self, parents):
parent1, parent2 = parents
child = [-1] * num_cities
start, end = sorted([random.randint(0, num_cities-1) for _ in range(2)])
for i in range(start, end+1):
child[i] = parent1.chromosome[i]
j = 0
for i in range(num_cities):
if child[i] == -1:
while parent2.chromosome[j] in child:
j += 1
child[i] = parent2.chromosome[j]
return Individual(child)
# 变异操作
def mutation(self, individual):
if random.random() < mutation_rate:
idx1, idx2 = sorted([random.randint(0, num_cities-1) for _ in range(2)])
individual.chromosome[idx1:idx2+1] = reversed(individual.chromosome[idx1:idx2+1])
individual.fitness = individual.calculate_fitness()
return individual
# 进化操作
def evolve(self):
parents = self.selection()
child = self.crossover(parents)
child = self.mutation(child)
self.population.append(child)
self.population = sorted(self.population, key=lambda x: x.fitness)[:self.size]
# 定义一个计算距离的函数
def calculate_distance(cities):
distance = [[0] * num_cities for _ in range(num_cities)]
for i in range(num_cities):
for j in range(i, num_cities):
distance[i][j] = distance[j][i] = ((cities[i][0]-cities[j][0])**2 + (cities[i][1]-cities[j][1])**2)**0.5
return distance
# 定义一个遗传算法函数
def genetic_algorithm(population_size, num_generations):
population = Population(population_size)
for i in range(num_generations):
population.evolve()
return population.population[0].chromosome, population.population[0].fitness
# 定义城市坐标和参数
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)]
num_cities = len(cities)
distance = calculate_distance(cities)
mutation_rate = 0.1
# 进行计算机模拟
for population_size in [10, 20, 50, 100, 1000, 10000]:
for num_generations in [1, 2, 3, 5, 10, 50, 100, 500, 1000]:
best_chromosome, best_fitness = genetic_algorithm(population_size, num_generations)
print(f"Population size: {population_size}, Num generations: {num_generations}, Best fitness: {best_fitness}")
```
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