attentionLayer函数,matlab代码
时间: 2023-06-19 20:10:01 浏览: 184
以下是一个简单的attentionLayer函数的Matlab代码示例:
```
function [weightedContext, attentionWeights] = attentionLayer(context, query, key, value)
% context: 输入上下文,大小为 [batchSize, contextLength, hiddenSize]
% query: 查询向量,大小为 [batchSize, queryLength, hiddenSize]
% key: 键向量,大小为 [batchSize, keyLength, hiddenSize]
% value: 值向量,大小为 [batchSize, valueLength, hiddenSize]
% 计算注意力分数
scores = query * permute(key, [1, 3, 2]); % 大小为 [batchSize, queryLength, keyLength]
attentionWeights = softmax(scores, 3); % 在最后一个维度上进行softmax,大小为 [batchSize, queryLength, keyLength]
% 对值向量进行加权求和
weightedContext = attentionWeights * value; % 大小为 [batchSize, queryLength, hiddenSize]
end
```
注意,这只是一个简单的实现示例,具体实现可能会因应用场景和需求而有所不同。
相关问题
matlab self attention layer
在 MATLAB 中实现 Self-Attention Layer,可以按照以下步骤进行:
1. 定义一个自注意力层的类,该类应该继承自 matlab.mixin.CustomDisplay 类,以便在命令窗口中显示自定义信息。
2. 在类的构造函数中设置自注意力层的参数,包括输入向量的维度、自注意力头的数量、隐藏层的大小等。
3. 实现自注意力层的前向传播函数,该函数应该接受输入向量并返回自注意力层的输出。在前向传播函数中,需要实现自注意力机制,包括计算注意力权重、加权求和等操作。
4. 实现自注意力层的反向传播函数,该函数应该接收反向传播的梯度并返回输入向量的梯度。在反向传播函数中,需要计算注意力权重的导数、加权求和的导数等。
下面是一个简单的 MATLAB 自注意力层的示例代码:
```matlab
classdef SelfAttentionLayer < matlab.mixin.CustomDisplay
properties
input_dim
num_heads
hidden_dim
dropout_rate
query_weights
key_weights
value_weights
end
methods
function obj = SelfAttentionLayer(input_dim, num_heads, hidden_dim, dropout_rate)
obj.input_dim = input_dim;
obj.num_heads = num_heads;
obj.hidden_dim = hidden_dim;
obj.dropout_rate = dropout_rate;
obj.query_weights = randn(hidden_dim, input_dim);
obj.key_weights = randn(hidden_dim, input_dim);
obj.value_weights = randn(hidden_dim, input_dim);
end
function output = forward(obj, input)
batch_size = size(input, 1);
query = input * obj.query_weights';
key = input * obj.key_weights';
value = input * obj.value_weights';
query = reshape(query, [batch_size, obj.num_heads, obj.hidden_dim/obj.num_heads]);
key = reshape(key, [batch_size, obj.num_heads, obj.hidden_dim/obj.num_heads]);
value = reshape(value, [batch_size, obj.num_heads, obj.hidden_dim/obj.num_heads]);
attention_weights = softmax(query * permute(key, [1, 3, 2]) / sqrt(obj.hidden_dim/obj.num_heads), 3);
attention_weights = dropout(attention_weights, obj.dropout_rate);
output = reshape(attention_weights * value, [batch_size, obj.hidden_dim]);
end
function input_gradient = backward(obj, output_gradient, input)
batch_size = size(input, 1);
query = input * obj.query_weights';
key = input * obj.key_weights';
value = input * obj.value_weights';
query = reshape(query, [batch_size, obj.num_heads, obj.hidden_dim/obj.num_heads]);
key = reshape(key, [batch_size, obj.num_heads, obj.hidden_dim/obj.num_heads]);
value = reshape(value, [batch_size, obj.num_heads, obj.hidden_dim/obj.num_heads]);
attention_weights = softmax(query * permute(key, [1, 3, 2]) / sqrt(obj.hidden_dim/obj.num_heads), 3);
attention_weights = dropout(attention_weights, obj.dropout_rate);
output_gradient = reshape(output_gradient, [batch_size, obj.num_heads, obj.hidden_dim/obj.num_heads]);
value_gradient = attention_weights' * output_gradient;
attention_weights_gradient = output_gradient * permute(value, [1, 3, 2]);
attention_weights_gradient = attention_weights_gradient .* (attention_weights .* (1-attention_weights));
attention_weights_gradient = dropout(attention_weights_gradient, obj.dropout_rate);
query_gradient = attention_weights_gradient * key;
key_gradient = permute(query, [1, 3, 2]) * attention_weights_gradient;
input_gradient = (query_gradient + key_gradient + value_gradient) * obj.query_weights;
end
function displayScalarObject(obj)
disp(['SelfAttentionLayer with input_dim = ', num2str(obj.input_dim), ', num_heads = ', num2str(obj.num_heads), ', hidden_dim = ', num2str(obj.hidden_dim), ', dropout_rate = ', num2str(obj.dropout_rate)]);
end
end
end
```
该代码使用了随机初始化的权重矩阵,实现了自注意力层的前向传播和反向传播函数,并添加了自定义信息的显示功能。
cnn-lstm-attention序列预测的matlab代码
以下是使用CNN-LSTM-Attention模型进行序列预测的MATLAB代码示例:
```matlab
% 加载数据
load data.mat
% 数据预处理
XTrain = permute(XTrain,[2 3 4 1]);
XTest = permute(XTest,[2 3 4 1]);
YTrain = categorical(YTrain);
YTest = categorical(YTest);
% 定义CNN层
layers = [
imageInputLayer([32 32 3])
convolution2dLayer(3,32,'Padding','same')
batchNormalizationLayer
reluLayer
maxPooling2dLayer(2,'Stride',2)
convolution2dLayer(3,64,'Padding','same')
batchNormalizationLayer
reluLayer
maxPooling2dLayer(2,'Stride',2)
convolution2dLayer(3,128,'Padding','same')
batchNormalizationLayer
reluLayer
maxPooling2dLayer(2,'Stride',2)
];
% 定义LSTM层
inputSize = 128;
numHiddenUnits = 64;
numClasses = 10;
lstmLayers = [
sequenceInputLayer(inputSize)
lstmLayer(numHiddenUnits,'OutputMode','last')
fullyConnectedLayer(numClasses)
softmaxLayer
classificationLayer
];
% 定义Attention层
attention = attentionLayer(numHiddenUnits);
% 将CNN和LSTM层连接起来
layers = [
layers
sequenceFoldingLayer('Name','fold')
lstmLayers
sequenceUnfoldingLayer('Name','unfold')
attention
];
% 定义训练选项
options = trainingOptions('adam', ...
'MaxEpochs',30, ...
'MiniBatchSize',64, ...
'Plots','training-progress');
% 训练模型
net = trainNetwork(XTrain,YTrain,layers,options);
% 测试模型
YPred = classify(net,XTest);
accuracy = sum(YPred == YTest)/numel(YTest);
disp(['Test accuracy: ' num2str(accuracy)])
```
需要注意的是,上述代码中用到的`attentionLayer`函数需要自行实现。你可以参考以下代码:
```matlab
classdef attentionLayer < nnet.layer.Layer
properties
HiddenSize
AttentionWeights
end
methods
function layer = attentionLayer(hiddenSize,name)
layer.HiddenSize = hiddenSize;
layer.Name = name;
layer.AttentionWeights = layer.initWeights(hiddenSize);
end
function weights = initWeights(~,hiddenSize)
weights = randn(hiddenSize,1);
end
function Z = predict(layer,X)
W = layer.AttentionWeights;
Z = tanh(W'*X);
end
function [dLdX,dLdW] = backward(layer,X,~,dLdZ,~)
W = layer.AttentionWeights;
Y = layer.predict(X);
dLdY = dLdZ.*(1-Y.^2);
dLdW = dLdY*X';
dLdX = W*dLdY;
end
end
end
```
这个实现只是一个简单的示例,你可以根据自己的需求进行修改和扩展。