bp神经网络 和lstm神经网络模型 代码基于pytorch

好的，非常感谢您的提问。以下是基于PyTorch实现BP神经网络和LSTM神经网络模型的代码示例：

BP神经网络模型代码示例：

import torch
import torch.nn as nn
import torch.optim as optim

# 定义BP神经网络模型
class BPNet(nn.Module):
    def __init__(self, input_dim, hidden_dim, output_dim):
        super(BPNet, self).__init__()
        self.fc1 = nn.Linear(input_dim, hidden_dim)
        self.fc2 = nn.Linear(hidden_dim, output_dim)

    def forward(self, x):
        x = torch.sigmoid(self.fc1(x))
        x = torch.sigmoid(self.fc2(x))
        return x

# 初始化模型
input_dim = 10
hidden_dim = 20
output_dim = 1
model = BPNet(input_dim, hidden_dim, output_dim)

# 定义损失函数和优化器
criterion = nn.MSELoss()
optimizer = optim.SGD(model.parameters(), lr=0.1)

# 训练模型
for epoch in range(100):
    # 前向传播计算预测值
    y_pred = model(x_train)

    # 计算损失
    loss = criterion(y_pred, y_train)

    # 反向传播更新模型参数
    optimizer.zero_grad()
    loss.backward()
    optimizer.step()

    # 打印训练过程
    if (epoch+1) % 10 == 0:
        print('Epoch [{}/{}], Loss: {:.4f}'.format(epoch+1, 100, loss.item()))

LSTM神经网络模型代码示例：

import torch
import torch.nn as nn
import torch.optim as optim

# 定义LSTM神经网络模型
class LSTMNet(nn.Module):
    def __init__(self, input_dim, hidden_dim, output_dim):
        super(LSTMNet, self).__init__()
        self.lstm = nn.LSTM(input_dim, hidden_dim, batch_first=True)
        self.fc = nn.Linear(hidden_dim, output_dim)

    def forward(self, x):
        out, _ = self.lstm(x)
        out = self.fc(out[:, -1, :])
        return out

# 初始化模型
input_dim = 10
hidden_dim = 20
output_dim = 1
model = LSTMNet(input_dim, hidden_dim, output_dim)

# 定义损失函数和优化器
criterion = nn.MSELoss()
optimizer = optim.SGD(model.parameters(), lr=0.1)

# 训练模型
for epoch in range(100):
    # 前向传播计算预测值
    y_pred = model(x_train)

    # 计算损失
    loss = criterion(y_pred, y_train)

    # 反向传播更新模型参数
    optimizer.zero_grad()
    loss.backward()
    optimizer.step()

    # 打印训练过程
    if (epoch+1) % 10 == 0:
        print('Epoch [{}/{}], Loss: {:.4f}'.format(epoch+1, 100, loss.item()))

以上是基于PyTorch实现BP神经网络和LSTM神经网络模型的代码示例，希望能对您有所帮助。