上面python的代码是什么
时间: 2024-05-18 18:15:54 浏览: 80
抱歉,我的回答有误,上面并没有给出Python代码。下面是一个Python实现的示例代码,可以用遗传算法求解f(x,y)=1+xsin(4πx)-ysin(4πy)+sin6√x²+y²/6√x²+y²+10的最大值:
```python
import random
import math
# 定义目标函数
def f(x, y):
return 1 + x * math.sin(4 * math.pi * x) - y * math.sin(4 * math.pi * y) + \
math.sin(6 * math.sqrt(x * x + y * y)) / (6 * math.sqrt(x * x + y * y) + 10)
# 定义个体编码
def encode(x):
return '{:016b}'.format(int(x * 1000))
# 定义个体解码
def decode(s):
return int(s, 2) / 1000
# 初始化种群
def init_population(size):
return [(random.uniform(-1, 1), random.uniform(-1, 1)) for i in range(size)]
# 计算适应度
def fitness(individual):
x, y = individual
return -f(x, y)
# 选择操作
def selection(population):
fitnesses = [fitness(individual) for individual in population]
total_fitness = sum(fitnesses)
probabilities = [fitness / total_fitness for fitness in fitnesses]
return random.choices(population, weights=probabilities, k=2)
# 交叉操作
def crossover(individual1, individual2, crossover_rate):
x1, y1 = individual1
x2, y2 = individual2
if random.random() < crossover_rate:
x1_bits, y1_bits = encode(x1), encode(y1)
x2_bits, y2_bits = encode(x2), encode(y2)
crossover_point = random.randint(1, 15)
offspring1 = (decode(x1_bits[:crossover_point] + y2_bits[crossover_point:]),
decode(y1_bits[:crossover_point] + x2_bits[crossover_point:]))
offspring2 = (decode(x2_bits[:crossover_point] + y1_bits[crossover_point:]),
decode(y2_bits[:crossover_point] + x1_bits[crossover_point:]))
return offspring1, offspring2
else:
return individual1, individual2
# 变异操作
def mutation(individual, mutation_rate):
x, y = individual
x_bits, y_bits = encode(x), encode(y)
mutated_x_bits = ''.join(['0' if bit == '1' else '1' if bit == '0' else bit for bit in x_bits])
mutated_y_bits = ''.join(['0' if bit == '1' else '1' if bit == '0' else bit for bit in y_bits])
mutated_x = decode(mutated_x_bits)
mutated_y = decode(mutated_y_bits)
if random.random() < mutation_rate:
return (mutated_x, y)
elif random.random() < mutation_rate:
return (x, mutated_y)
else:
return individual
# 更新种群
def evolve(population, selection_size, crossover_rate, mutation_rate):
selected = [selection(population) for i in range(selection_size)]
offspring = [crossover(*parents, crossover_rate) for parents in selected]
mutated = [mutation(individual, mutation_rate) for individual in offspring]
new_population = [mutation(individual, mutation_rate) for individual in population]
new_population.extend(mutated)
fitnesses = [fitness(individual) for individual in new_population]
ranked_population = sorted(zip(new_population, fitnesses), key=lambda x: x[1], reverse=True)
return [individual for individual, fitness in ranked_population][:len(population)]
# 定义遗传算法函数
def genetic_algorithm(population_size, selection_size, crossover_rate, mutation_rate, generations):
population = init_population(population_size)
for i in range(generations):
population = evolve(population, selection_size, crossover_rate, mutation_rate)
best_individual = max(population, key=fitness)
print('Generation', i+1, ': best individual =', best_individual, ', best fitness =', -fitness(best_individual))
return max(population, key=fitness)
# 运行遗传算法
best_individual = genetic_algorithm(population_size=100, selection_size=50, crossover_rate=0.8, mutation_rate=0.01, generations=100)
print('Best individual found:', best_individual)
print('Best fitness found:', -fitness(best_individual))
```
这段代码使用了二进制编码来表示个体,其中每个变量x和y都用16位二进制数表示,前8位表示整数部分,后8位表示小数部分。在遗传算法中,使用了轮盘赌选择算法、单点交叉和单点变异等操作。在每一代种群中,都可以输出最好的个体和最好的适应度。
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