遗传算法代码怎么跑出收敛图
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遗传算法代码解析与实现
遗传算法(Genetic Algorithm, GA)是一种模拟自然选择和遗传机制的优化算法,常用于解决搜索和优化问题。以下是一个简单的遗传算法的Python实现:
import random
适应度函数(fitness function),针对特定问题定义
def fitness_function(solution):
这里假设解是一个列表,计算列表元素之和作为适应度
return sum(solution)
初始化种群
def initialize_population(population_size, chromosome_length):
population = []
for _ in range(population_size):
生成一个随机解(染色体)
chromosome = [random.randint(0, 1) for _ in range(chromosome_length)]
population.append(chromosome)
return population
选择操作
def selection(population, fitness_values):
使用轮盘赌选择法
total_fitness = sum(fitness_values)
selection_probabilities = [fitness / total_fitness for fitness in fitness_values]
selected_index = random.choices(range(len(population)), weights=selection_probabilities)[0]
return population[selected_index]
交叉操作
def crossover(parent1, parent2):
crossover_point = random.randint(1, len(parent1) 1)
child1 = parent1[:crossover_point] parent2[crossover_point:]
child2 = parent2[:crossover_point] parent1[crossover_point:]
return child1, child2
变异操作
def mutation(chromosome, mutation_rate):
for i in range(len(chromosome)):
if random.random() < mutation_rate:
chromosome[i] = 1 chromosome[i]
return chromosome
主要遗传算法函数
def genetic_algorithm(population_size, chromosome_length, generations, mutation_rate):
population = initialize_population(population_size, chromosome_length)
for _ in range(generations):
fitness_values = [fitness_function(chromosome) for chromosome in population]
new_population = []
for _ in range(population_size // 2):
parent1 = selection(population, fitness_values)
parent2 = selection(population, fitness_values)
child1, child2 = crossover(parent1, parent2)
child1 = mutation(child1, mutation_rate)
child2 = mutation(child2, mutation_rate)
new_population.extend([child1, child2])
population = new_population
返回最优解
best_solution = max(population, key=fitness_function)
return best_solution
测试
population_size = 100
chromosome_length = 10
generations = 50
mutation_rate = 0.01
best_solution = genetic_algorithm(population_size, chromosome_length, generations, mutation_rate)
print("Best Solution:", best_solution)
print("Fitness:", fitness_function(best_solution))
这段代码演示了一个简单的遗传算法的实现过程,其中包括初始化种群、选择、交叉、变异等操作。你可以根据具体的问题,调整参数和适应度函数,以解决不同的优化问题。