贝叶斯优化算法matlab解决旅行商问题
时间: 2023-09-21 16:06:56 浏览: 96
贝叶斯优化算法一般用于黑盒函数的优化,而旅行商问题属于组合优化问题,因此不太适合用贝叶斯优化算法求解。不过,可以使用遗传算法、模拟退火等算法来求解旅行商问题。下面给出一个使用遗传算法求解旅行商问题的 Matlab 代码示例:
```
% 城市坐标
city = [0 0; 1 1; 2 2; 3 3; 4 4; 5 5; 6 6; 7 7];
% 城市数量
n = size(city, 1);
% 初始化种群大小
pop_size = 100;
% 初始化交叉率和变异率
cr = 0.9;
mr = 0.05;
% 初始化种群
pop = zeros(pop_size, n);
for i = 1:pop_size
pop(i, :) = randperm(n);
end
% 计算适应度
fitness = zeros(pop_size, 1);
for i = 1:pop_size
fitness(i) = cal_fitness(pop(i, :), city);
end
% 迭代次数
iter_num = 100;
for iter = 1:iter_num
% 记录迭代过程中的最优解和最优适应度
[best_fitness, idx] = min(fitness);
best_solution = pop(idx, :);
% 选择操作
new_pop = zeros(pop_size, n);
for i = 1:pop_size
% 锦标赛选择
idx1 = randi(pop_size);
idx2 = randi(pop_size);
if fitness(idx1) < fitness(idx2)
p1 = pop(idx1, :);
else
p1 = pop(idx2, :);
end
idx1 = randi(pop_size);
idx2 = randi(pop_size);
if fitness(idx1) < fitness(idx2)
p2 = pop(idx1, :);
else
p2 = pop(idx2, :);
end
% 交叉操作
if rand() < cr
c = randi(n);
new_pop(i, :) = [p1(1:c) p2(c+1:end)];
else
new_pop(i, :) = p1;
end
% 变异操作
if rand() < mr
idx1 = randi(n);
idx2 = randi(n);
new_pop(i, [idx1 idx2]) = new_pop(i, [idx2 idx1]);
end
end
% 更新种群和适应度
pop = new_pop;
for i = 1:pop_size
fitness(i) = cal_fitness(pop(i, :), city);
end
end
% 输出结果
disp(['最优解:', num2str(best_solution)]);
disp(['最优适应度:', num2str(best_fitness)]);
% 计算适应度函数
function f = cal_fitness(solution, city)
n = size(city, 1);
d = 0;
for i = 1:n-1
d = d + norm(city(solution(i+1), :) - city(solution(i), :));
end
d = d + norm(city(solution(1), :) - city(solution(n), :));
f = 1 / d;
end
```
该代码使用了遗传算法来求解旅行商问题,其中种群大小为100,交叉率为0.9,变异率为0.05。在迭代100次之后,程序输出最优解和最优适应度。注意,该代码并不能保证一定求解出最优解,因为遗传算法是一种启发式算法,只能得到近似最优解。
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