编写pytorch代码,定义LSTMAttention模型,在参数空间定义学习率、batch_size、权重衰减、神经元个数、dropout、自注意力等超参数,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算法优化模型中超参数,找到最优的超参数组合,并将最优的超参数传递给模型
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好的,我来解答这个问题。首先,我们需要定义LSTMAttention模型,代码如下:
```python
import torch
import torch.nn as nn
import torch.nn.functional as F
class LSTMAttention(nn.Module):
def __init__(self, input_dim, hidden_dim, output_dim):
super(LSTMAttention, self).__init__()
self.lstm = nn.LSTM(input_dim, hidden_dim, batch_first=True)
self.attention_fc = nn.Linear(hidden_dim, 1)
self.fc = nn.Linear(hidden_dim, output_dim)
def forward(self, x):
out, (h_n, c_n) = self.lstm(x)
attention_weights = F.softmax(self.attention_fc(out), dim=1)
context_vector = torch.sum(attention_weights * out, dim=1)
output = self.fc(context_vector)
return output
```
接下来,我们需要定义模型的超参数空间和优化算法。这里我们使用CPSO算法来优化模型的超参数,代码如下:
```python
import random
class CPSO:
def __init__(self, num_particles, dim, max_iter, lr):
self.num_particles = num_particles
self.dim = dim
self.max_iter = max_iter
self.lr = lr
self.particles = [[random.uniform(0, 1) for _ in range(dim)] for _ in range(num_particles)]
self.velocities = [[0 for _ in range(dim)] for _ in range(num_particles)]
self.pbest_positions = self.particles.copy()
self.pbest_fitnesses = [float('inf') for _ in range(num_particles)]
self.gbest_position = [0 for _ in range(dim)]
self.gbest_fitness = float('inf')
def update_position(self, x, v):
return [xi + vi for xi, vi in zip(x, v)]
def update_velocity(self, x, v, pbest, gbest):
w = 0.7
c1 = 1.4
c2 = 1.4
r1 = random.uniform(0, 1)
r2 = random.uniform(0, 1)
v_new = [w * vi + c1 * r1 * (pbest[i] - xi) + c2 * r2 * (gbest[i] - xi) for i, xi, vi in zip(range(self.dim), x, v)]
return v_new
def evaluate_fitness(self, fitness_function):
fitnesses = []
for particle in self.particles:
fitness = fitness_function(particle)
fitnesses.append(fitness)
if fitness < self.pbest_fitnesses[self.particles.index(particle)]:
self.pbest_fitnesses[self.particles.index(particle)] = fitness
self.pbest_positions[self.particles.index(particle)] = particle
if fitness < self.gbest_fitness:
self.gbest_fitness = fitness
self.gbest_position = particle
return fitnesses
def optimize(self, fitness_function):
for i in range(self.max_iter):
fitnesses = self.evaluate_fitness(fitness_function)
for particle, velocity in zip(self.particles, self.velocities):
velocity = self.update_velocity(particle, velocity, self.pbest_positions[self.particles.index(particle)], self.gbest_position)
particle = self.update_position(particle, velocity)
self.velocities = [self.update_velocity(particle, velocity, self.pbest_positions[self.particles.index(particle)], self.gbest_position) for particle, velocity in zip(self.particles, self.velocities)]
self.particles = [self.update_position(particle, velocity) for particle, velocity in zip(self.particles, self.velocities)]
return self.gbest_position
```
接下来,我们需要定义适应度函数fitness_function,用于评估LSTMAttention模型在给定超参数下的性能。这里我们使用交叉熵损失函数和Adam优化算法来训练模型,代码如下:
```python
import torch.optim as optim
import torch.utils.data as data
def fitness_function(hyperparameters):
# set hyperparameters
learning_rate = hyperparameters[0]
batch_size = int(hyperparameters[1] * 128)
weight_decay = hyperparameters[2]
hidden_dim = int(hyperparameters[3] * 256)
dropout = hyperparameters[4]
num_heads = int(hyperparameters[5] * 8)
# define model
model = LSTMAttention(input_dim=10, hidden_dim=hidden_dim, output_dim=2)
# define optimizer and loss function
optimizer = optim.Adam(model.parameters(), lr=learning_rate, weight_decay=weight_decay)
criterion = nn.CrossEntropyLoss()
# train model
for epoch in range(10):
for i, (x, y) in enumerate(train_loader):
optimizer.zero_grad()
output = model(x)
loss = criterion(output, y)
loss.backward()
optimizer.step()
# evaluate model
correct = 0
total = 0
with torch.no_grad():
for x, y in test_loader:
output = model(x)
_, predicted = torch.max(output.data, 1)
total += y.size(0)
correct += (predicted == y).sum().item()
accuracy = correct / total
return accuracy
```
最后,我们可以使用CPSO算法来优化模型的超参数,找到最优的超参数组合,并将最优的超参数传递给模型,代码如下:
```python
# define train and test data loaders
train_loader = data.DataLoader(train_data, batch_size=128, shuffle=True)
test_loader = data.DataLoader(test_data, batch_size=128, shuffle=True)
# define hyperparameters space and CPSO optimizer
hyperparameters_space = [(1e-5, 1e-1), (0.1, 1), (1e-5, 1e-1), (0.1, 1), (0, 0.5), (0.1, 1)]
num_particles = 20
dim = len(hyperparameters_space)
max_iter = 50
lr = 0.1
cpso = CPSO(num_particles, dim, max_iter, lr)
# optimize hyperparameters using CPSO algorithm
best_hyperparameters = cpso.optimize(fitness_function)
# set best hyperparameters to model
learning_rate = best_hyperparameters[0]
batch_size = int(best_hyperparameters[1] * 128)
weight_decay = best_hyperparameters[2]
hidden_dim = int(best_hyperparameters[3] * 256)
dropout = best_hyperparameters[4]
num_heads = int(best_hyperparameters[5] * 8)
model = LSTMAttention(input_dim=10, hidden_dim=hidden_dim, output_dim=2)
optimizer = optim.Adam(model.parameters(), lr=learning_rate, weight_decay=weight_decay)
```
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