详细分析一下python代码:import torch.optim as optim criterion = nn.CrossEntropyLoss() optimizer = optim.Adam(net.parameters(), lr=0.01, betas=(0.9, 0.999), eps=1e-08, weight_decay=0, amsgrad=False) scheduler = optim.lr_scheduler.ReduceLROnPlateau(optimizer, mode='min', factor=0.1, patience=10, verbose=True, min_lr=0) loss_hist, acc_hist = [], [] loss_hist_val, acc_hist_val = [], [] for epoch in range(140): running_loss = 0.0 correct = 0 for data in train_loader: batch, labels = data batch, labels = batch.to(device), labels.to(device) optimizer.zero_grad() outputs = net(batch) loss = criterion(outputs, labels) loss.backward() optimizer.step() # compute training statistics _, predicted = torch.max(outputs, 1) correct += (predicted == labels).sum().item() running_loss += loss.item() avg_loss = running_loss / len(train_set) avg_acc = correct / len(train_set) loss_hist.append(avg_loss) acc_hist.append(avg_acc) # validation statistics net.eval() with torch.no_grad(): loss_val = 0.0 correct_val = 0 for data in val_loader: batch, labels = data batch, labels = batch.to(device), labels.to(device) outputs = net(batch) loss = criterion(outputs, labels) _, predicted = torch.max(outputs, 1) correct_val += (predicted == labels).sum().item() loss_val += loss.item() avg_loss_val = loss_val / len(val_set) avg_acc_val = correct_val / len(val_set) loss_hist_val.append(avg_loss_val) acc_hist_val.append(avg_acc_val) net.train() scheduler.step(avg_loss_val) print('[epoch %d] loss: %.5f accuracy: %.4f val loss: %.5f val accuracy: %.4f' % (epoch + 1, avg_loss, avg_acc, avg_loss_val, avg_acc_val))
时间: 2024-04-02 11:37:22 浏览: 167
利用torch.nn实现二维卷积python代码
这段代码是一个基于PyTorch的神经网络训练过程。代码中使用了torch.optim模块中Adam优化器和ReduceLROnPlateau学习率调度器。其中,Adam优化器用于优化网络的参数,而ReduceLROnPlateau调度器用于自动调整学习率以提高训练效果。代码中使用nn.CrossEntropyLoss()作为损失函数,用于计算输出结果与标签之间的差距。
接下来的代码中使用了两个循环,一个是对训练数据集的循环,另一个是对验证数据集的循环。在训练数据集循环中,首先将数据集分成一个个batch,然后将batch和对应的标签传入网络进行前向传播,计算损失值,然后进行反向传播和参数更新。在这个过程中,记录了每个batch的正确预测个数和损失值,最后计算平均损失和准确率,并将其保存在loss_hist和acc_hist列表中。
在验证数据集循环中,同样将数据集分成一个个batch,然后将batch和对应的标签传入网络进行前向传播,计算损失值,并计算正确预测个数。最后将每个batch的平均损失和准确率记录在loss_hist_val和acc_hist_val列表中。
在每个epoch结束后,调用scheduler.step(avg_loss_val)方法来更新学习率,并打印出当前epoch的训练和验证结果。其中,avg_loss和avg_acc记录了该epoch的训练结果,avg_loss_val和avg_acc_val记录了该epoch的验证结果。
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