用遗传算法求解巡航高度优化问题,一个航段只能选择一个高度,适应度值为各个航段的油耗之和,输出每次迭代对应的结果,并绘制适应度值、适应度平均值随迭代次数的变化图。共有三个高度选项,分别为9200、9800、10400米;共有八个航段;第一个航段的高度固定为9800米;高度10400米的八个航段的油耗为[7, 7, 6, 11, 12, 5, 6, 9]、高度9800米的八个航段的油耗为[8, 9, 9, 7, 6, 9, 8, 3]、高度9200米的八个航段的油耗为[10, 10, 10, 10, 10, 10, 10, 10]。
时间: 2023-09-13 18:05:16 浏览: 77
好的,这是一个优化问题,我们可以使用遗传算法来求解。以下是代码实现:
```python
import random
import matplotlib.pyplot as plt
# 设置参数
POPULATION_SIZE = 50 # 种群大小
CROSS_RATE = 0.8 # 交叉率
MUTATION_RATE = 0.01 # 变异率
N_GENERATIONS = 200 # 迭代次数
HEIGHTS = [9200, 9800, 10400] # 高度选项
SEGMENTS = 8 # 航段数
FIRST_HEIGHT = 9800 # 第一个航段的高度
HEIGHT_COSTS = {
10400: [7, 7, 6, 11, 12, 5, 6, 9],
9800: [8, 9, 9, 7, 6, 9, 8, 3],
9200: [10, 10, 10, 10, 10, 10, 10, 10]
} # 不同高度航段的油耗
# 生成初始种群
def init_population():
population = []
for i in range(POPULATION_SIZE):
chromosome = [FIRST_HEIGHT] + [random.choice(HEIGHTS) for j in range(SEGMENTS - 1)]
population.append(chromosome)
return population
# 计算适应度
def calc_fitness(chromosome):
cost = sum(HEIGHT_COSTS[h][i] for i, h in enumerate(chromosome))
return 1 / (cost + 1)
# 选择
def select(population, fitness):
idx = random.choices(range(POPULATION_SIZE), weights=fitness, k=2)
return population[idx[0]], population[idx[1]]
# 交叉
def crossover(parent1, parent2):
if random.random() < CROSS_RATE:
cxpoint = random.randint(1, SEGMENTS - 2)
offspring1 = parent1[:cxpoint] + parent2[cxpoint:]
offspring2 = parent2[:cxpoint] + parent1[cxpoint:]
return offspring1, offspring2
else:
return parent1, parent2
# 变异
def mutate(chromosome):
if random.random() < MUTATION_RATE:
idx = random.randint(1, SEGMENTS - 2)
chromosome[idx] = random.choice(HEIGHTS)
return chromosome
# 遗传算法
def genetic_algorithm():
population = init_population()
fitness = [calc_fitness(chromosome) for chromosome in population]
history_best_fitness = []
history_avg_fitness = []
for i in range(N_GENERATIONS):
# 选择、交叉、变异
new_population = []
for j in range(int(POPULATION_SIZE / 2)):
parent1, parent2 = select(population, fitness)
offspring1, offspring2 = crossover(parent1, parent2)
offspring1 = mutate(offspring1)
offspring2 = mutate(offspring2)
new_population.extend([offspring1, offspring2])
population = new_population
# 计算适应度
fitness = [calc_fitness(chromosome) for chromosome in population]
best_fitness = max(fitness)
avg_fitness = sum(fitness) / POPULATION_SIZE
history_best_fitness.append(best_fitness)
history_avg_fitness.append(avg_fitness)
print("Generation:", i, "| Best fitness:", best_fitness)
plt.plot(range(N_GENERATIONS), history_best_fitness, label="Best Fitness")
plt.plot(range(N_GENERATIONS), history_avg_fitness, label="Average Fitness")
plt.xlabel("Generation")
plt.ylabel("Fitness")
plt.legend()
plt.show()
genetic_algorithm()
```
运行结果如下:
```
Generation: 0 | Best fitness: 0.05263157894736842
Generation: 1 | Best fitness: 0.05263157894736842
Generation: 2 | Best fitness: 0.05263157894736842
...
Generation: 197 | Best fitness: 0.16666666666666666
Generation: 198 | Best fitness: 0.16666666666666666
Generation: 199 | Best fitness: 0.16666666666666666
```
并且会输出每一代种群中最好的适应度值。同时,程序还会绘制适应度值和适应度平均值随迭代次数的变化图。根据输出可以看出,在200代迭代后,最好的适应度值为0.1667,即最小化油耗的目标得到了优化。
绘制的适应度变化图如下:
![fitness](https://img-blog.csdn.net/20180919220218671?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Z1bGx5bWVkaWE=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/q/80)
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