1. 数据预处理
代码块
% 数据归一化(Z-score标准化)
[X_norm, X_ps] = mapminmax(X', 0, 1);
Y_norm = mapminmax(Y', 0, 1)';
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2. BP网络初始化
代码块
input_neurons = size(X,2);
hidden_neurons = 10; % 隐含层节点数
output_neurons = size(Y,2);
% 初始化权值矩阵
W1 = rand(input_neurons, hidden_neurons);
W2 = rand(hidden_neurons, output_neurons);
B1 = rand(1, hidden_neurons);
B2 = rand(1, output_neurons);
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3. 蚁群算法优化
代码块
num_ants = 20; % 蚂蚁数量
max_iter = 100; % 最大迭代次数
Q = 100; % 信息素增强强度
% 初始化信息素矩阵
pheromone = ones(size(W1,1)*size(W1,2) + size(W2,1)*size(W2,2) + ...
size(B1,2) + size(B2,2), 1);
for iter = 1:max_iter
for ant = 1:num_ants
% 解码蚂蚁路径为权值组合
[W1_ant, W2_ant, B1_ant, B2_ant] = decode_path(pheromone, ant);
% 计算适应度(预测误差)
net = feedforwardnet(hidden_neurons);
net.trainParam.showWindow = false;
net = configure(net, X_norm', Y_norm');
net.IW{1,1} = W1_ant;
net.LW{2,1} = W2_ant;
net.b{1} = B1_ant;
net.b{2} = B2_ant;
[net, tr] = train(net, X_norm', Y_norm');
error = perform(net, Y_norm', net(X_norm'));
% 更新信息素
pheromone = (1-0.1)*pheromone + Q*error;
end
end
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4. 模型训练与预测
代码块
% 使用最优权值训练BP网络
net = train(net, X_norm', Y_norm');
% 预测与反归一化
Y_pred_norm = net(X_norm');
Y_pred = mapminmax('reverse', Y_pred_norm', Y_ps)';
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适应度函数改进
代码块
function error = fitness(ant_path, X, Y)
% 解码路径为权值
[W1, W2, B1, B2] = decode(ant_path);
% 构建网络
net = feedforwardnet(10);
net.IW{1,1} = W1;
net.LW{2,1} = W2;
net.b{1} = B1;
net.b{2} = B2;
% 计算预测误差
Y_pred = net(X');
error = mean((Y' - Y_pred).^2); % MSE
end
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信息素更新策略
elite_ratio = 0.1;
elite_indices = 1:ceil(elite_ratio*num_ants);
pheromone(elite_indices) = pheromone(elite_indices) * 1.5;
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