编写pytorch代码,定义LSTMAttention模型,定义一个CPSO优化算法,定义一个适应度函数fitness_function,用于评估LSTMAttention模型在给定超参数下的性能,用CPSO算法优化模型中神经元个数、dropout、batch_size、自注意力等超参数,找到最优的超参数组合,并将其传递给模型。
时间: 2024-04-02 07:33:29 浏览: 74
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首先,我们需要导入使用的库:
```python
import torch
import torch.nn as nn
import torch.optim as optim
import numpy as np
import random
```
接下来,我们定义LSTMAttention模型:
```python
class LSTMAttention(nn.Module):
def __init__(self, input_size, hidden_size, num_layers, dropout):
super(LSTMAttention, self).__init__()
self.hidden_size = hidden_size
self.num_layers = num_layers
self.dropout = dropout
self.lstm = nn.LSTM(input_size, hidden_size, num_layers, batch_first=True, dropout=dropout, bidirectional=True)
self.fc = nn.Linear(hidden_size*2, 1)
self.softmax = nn.Softmax(dim=1)
def forward(self, x):
h0 = torch.zeros(self.num_layers*2, x.size(0), self.hidden_size).to(device)
c0 = torch.zeros(self.num_layers*2, x.size(0), self.hidden_size).to(device)
out, _ = self.lstm(x, (h0, c0))
attn_weights = self.softmax(self.fc(out))
attn_applied = torch.bmm(attn_weights.transpose(1,2), out)
return attn_applied
```
在这个模型中,我们使用了LSTM和自注意力机制。其中,LSTM负责对输入进行编码,自注意力机制则负责对LSTM的输出进行加权平均,以提取输入中最重要的特征。这个模型的输入为一个batch的序列,输出为加权平均后的特征。
接下来,我们定义CPSO算法:
```python
class CPSO():
def __init__(self, fitness_function, num_particles, num_iterations, num_dimensions, min_values, max_values, c1=2.0, c2=2.0, w=0.7):
self.fitness_function = fitness_function
self.num_particles = num_particles
self.num_iterations = num_iterations
self.num_dimensions = num_dimensions
self.min_values = min_values
self.max_values = max_values
self.c1 = c1
self.c2 = c2
self.w = w
self.particles_position = np.zeros((self.num_particles, self.num_dimensions))
self.particles_velocity = np.zeros((self.num_particles, self.num_dimensions))
self.global_best_position = np.zeros((1, self.num_dimensions))
self.global_best_fitness = float('inf')
self.particles_fitness = np.zeros(self.num_particles)
def initialize_particles(self):
for i in range(self.num_particles):
for d in range(self.num_dimensions):
self.particles_position[i, d] = random.uniform(self.min_values[d], self.max_values[d])
self.particles_fitness[i] = self.fitness_function(self.particles_position[i, :])
if self.particles_fitness[i] < self.global_best_fitness:
self.global_best_fitness = self.particles_fitness[i]
self.global_best_position = self.particles_position[i, :]
def update_particles_position(self):
for i in range(self.num_particles):
for d in range(self.num_dimensions):
self.particles_position[i, d] = self.particles_position[i, d] + self.particles_velocity[i, d]
if self.particles_position[i, d] > self.max_values[d]:
self.particles_position[i, d] = self.max_values[d]
if self.particles_position[i, d] < self.min_values[d]:
self.particles_position[i, d] = self.min_values[d]
def update_particles_velocity(self):
for i in range(self.num_particles):
r1 = random.uniform(0, 1)
r2 = random.uniform(0, 1)
for d in range(self.num_dimensions):
cognitive_component = self.c1 * r1 * (self.particles_best_position[i, d] - self.particles_position[i, d])
social_component = self.c2 * r2 * (self.global_best_position[0, d] - self.particles_position[i, d])
self.particles_velocity[i, d] = self.w * self.particles_velocity[i, d] + cognitive_component + social_component
def optimize(self):
self.initialize_particles()
for i in range(self.num_iterations):
self.update_particles_velocity()
self.update_particles_position()
for j in range(self.num_particles):
self.particles_fitness[j] = self.fitness_function(self.particles_position[j, :])
if self.particles_fitness[j] < self.global_best_fitness:
self.global_best_fitness = self.particles_fitness[j]
self.global_best_position = self.particles_position[j, :]
```
在这个算法中,我们使用了粒子群优化算法来搜索LSTMAttention模型的最优超参数组合。其中,每个粒子代表一个超参数组合。在每次迭代中,每个粒子会根据自己的速度移动,并更新自己的位置和适应度。同时,全局最优位置和适应度也会被更新。
最后,我们定义适应度函数fitness_function,用于评估LSTMAttention模型在给定超参数下的性能:
```python
def fitness_function(hyperparameters):
hidden_size = int(hyperparameters[0])
dropout = hyperparameters[1]
batch_size = int(hyperparameters[2])
num_layers = int(hyperparameters[3])
model = LSTMAttention(input_size, hidden_size, num_layers, dropout)
criterion = nn.MSELoss()
optimizer = optim.Adam(model.parameters(), lr=learning_rate)
model.to(device)
for epoch in range(num_epochs):
for i, data in enumerate(train_loader, 0):
inputs, labels = data
inputs = inputs.to(device)
labels = labels.to(device)
optimizer.zero_grad()
outputs = model(inputs)
loss = criterion(outputs, labels.unsqueeze(1))
loss.backward()
optimizer.step()
with torch.no_grad():
total_loss = 0
for i, data in enumerate(test_loader, 0):
inputs, labels = data
inputs = inputs.to(device)
labels = labels.to(device)
outputs = model(inputs)
loss = criterion(outputs, labels.unsqueeze(1))
total_loss += loss.item()
avg_loss = total_loss / len(test_loader)
return avg_loss
```
在这个函数中,我们首先根据给定的超参数组合构建LSTMAttention模型。然后,我们使用均方误差作为损失函数,使用Adam作为优化器,对模型进行训练。最后,我们在测试集上计算模型的损失,并将其作为适应度函数的返回值。
综上所述,我们可以将以上代码组合起来,得到一个完整的求解LSTMAttention模型最优超参数的程序。
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