给出已知十四个地点之间的距离矩阵,求经过十四个地点的最短路劲,每个地点有且仅经过一次。用mtalab语言求解
时间: 2024-03-17 18:42:53 浏览: 56
用matlab实现的最短路径算法
这个问题可以用MATLAB语言中的遗传算法来求解,下面是MATLAB代码示例:
```matlab
% 输入距离矩阵
dist_matrix = [
0 2 3 4 5 6 7 8 9 10 11 12 13 14;
2 0 3 4 5 6 7 8 9 10 11 12 13 14;
3 3 0 4 5 6 7 8 9 10 11 12 13 14;
4 4 4 0 5 6 7 8 9 10 11 12 13 14;
5 5 5 5 0 6 7 8 9 10 11 12 13 14;
6 6 6 6 6 0 7 8 9 10 11 12 13 14;
7 7 7 7 7 7 0 8 9 10 11 12 13 14;
8 8 8 8 8 8 8 0 9 10 11 12 13 14;
9 9 9 9 9 9 9 9 0 10 11 12 13 14;
10 10 10 10 10 10 10 10 10 0 11 12 13 14;
11 11 11 11 11 11 11 11 11 11 0 12 13 14;
12 12 12 12 12 12 12 12 12 12 12 0 13 14;
13 13 13 13 13 13 13 13 13 13 13 13 0 14;
14 14 14 14 14 14 14 14 14 14 14 14 14 0
];
% 定义遗传算法参数
pop_size = 100; % 种群大小
num_generations = 500; % 迭代次数
mutation_rate = 0.01; % 变异率
% 定义适应度函数,计算路径长度
fitness_func = @(path) path_length(path, dist_matrix);
% 初始化种群
population = init_population(pop_size, size(dist_matrix, 1));
% 迭代遗传算法
for i = 1:num_generations
% 计算适应度
fitness = arrayfun(fitness_func, population);
% 选择
parents = select_parents(population, fitness);
% 杂交
offspring = crossover(parents, pop_size);
% 变异
mutated_offspring = mutate(offspring, mutation_rate);
% 合并父代和子代
combined_population = [population; mutated_offspring];
% 计算适应度
combined_fitness = arrayfun(fitness_func, combined_population);
% 选择下一代种群
population = select_population(combined_population, combined_fitness, pop_size);
end
% 打印最优解
best_path = population(1, :);
fprintf('Best path: ');
fprintf('%d ', best_path);
fprintf('\nPath length: %f\n', path_length(best_path, dist_matrix));
% 定义初始化种群函数
function pop = init_population(pop_size, num_nodes)
pop = zeros(pop_size, num_nodes);
for i = 1:pop_size
pop(i, :) = randperm(num_nodes);
end
end
% 定义选择函数(锦标赛选择)
function selected = select_parents(population, fitness)
num_parents = size(population, 1);
selected = zeros(num_parents, size(population, 2));
for i = 1:num_parents
% 随机选择两个个体进行比较
idx1 = randi(size(population, 1));
idx2 = randi(size(population, 1));
if fitness(idx1) < fitness(idx2)
selected(i, :) = population(idx1, :);
else
selected(i, :) = population(idx2, :);
end
end
end
% 定义杂交函数(顺序交叉)
function offspring = crossover(parents, num_offspring)
num_parents = size(parents, 1);
offspring = zeros(num_offspring, size(parents, 2));
for i = 1:num_offspring
% 随机选择两个父代进行杂交
idx1 = randi(num_parents);
idx2 = randi(num_parents);
parent1 = parents(idx1, :);
parent2 = parents(idx2, :);
% 随机选择杂交点
crossover_point = randi(size(parent1, 2));
% 进行杂交
offspring(i, :) = [parent1(1:crossover_point), parent2(crossover_point+1:end)];
end
end
% 定义变异函数(随机交换两个节点)
function mutated_offspring = mutate(offspring, mutation_rate)
mutated_offspring = offspring;
num_mutations = ceil(mutation_rate * size(offspring, 1) * size(offspring, 2));
for i = 1:num_mutations
idx1 = randi(size(offspring, 1));
idx2 = randi(size(offspring, 2));
idx3 = randi(size(offspring, 2));
temp = mutated_offspring(idx1, idx2);
mutated_offspring(idx1, idx2) = mutated_offspring(idx1, idx3);
mutated_offspring(idx1, idx3) = temp;
end
end
% 定义选择下一代种群函数(精英保留)
function selected = select_population(population, fitness, pop_size)
[~, idx] = sort(fitness);
selected = population(idx(1:pop_size), :);
end
% 定义计算路径长度函数
function length = path_length(path, dist_matrix)
length = 0;
for i = 1:length(path)-1
length = length + dist_matrix(path(i), path(i+1));
end
end
```
在这个示例代码中,我们定义了一个适应度函数,它计算遗传算法中的路径长度。然后,我们使用遗传算法进行迭代优化,找到经过所有节点的最短路径。最后,我们输出最优解和路径长度。
注意,这只是一个示例代码,你需要根据你的具体问题来修改代码。
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