model = ResNet_101(num_classes=20) model.load_state_dict(torch.load("../models/train-01-0.8536.pth"))

这段代码用于加载预训练的`ResNet_101`模型的状态字典。`ResNet_101`是一个继承自`nn.Module`的PyTorch模型，它的初始化方法接受一个参数`num_classes`，表示最终的分类数。在这里，你首先实例化了一个`ResNet_101`模型对象，并将它的`num_classes`参数设置为20。接下来，你使用`torch.load()`方法从磁盘上加载已经训练好的模型的状态字典。这个方法接受一个文件路径作为输入，并返回一个包含模型状态字典的Python字典对象。你将这个状态字典对象通过`model.load_state_dict()`方法加载到你的模型中，以便将已经训练好的权重和偏置值加载到你的模型中以进行预测。

相关问题

LDAM损失函数pytorch代码如下：class LDAMLoss(nn.Module): def init(self, cls_num_list, max_m=0.5, weight=None, s=30): super(LDAMLoss, self).init() m_list = 1.0 / np.sqrt(np.sqrt(cls_num_list)) m_list = m_list * (max_m / np.max(m_list)) m_list = torch.cuda.FloatTensor(m_list) self.m_list = m_list assert s > 0 self.s = s if weight is not None: weight = torch.FloatTensor(weight).cuda() self.weight = weight self.cls_num_list = cls_num_list def forward(self, x, target): index = torch.zeros_like(x, dtype=torch.uint8) index_float = index.type(torch.cuda.FloatTensor) batch_m = torch.matmul(self.m_list[None, :], index_float.transpose(1,0)) # 0,1 batch_m = batch_m.view((16, 1)) # size=(batch_size, 1) (-1,1) x_m = x - batch_m output = torch.where(index, x_m, x) if self.weight is not None: output = output * self.weight[None, :] target = torch.flatten(target) # 将 target 转换成 1D Tensor logit = output * self.s return F.cross_entropy(logit, target, weight=self.weight) 模型部分参数如下：# 设置全局参数 model_lr = 1e-5 BATCH_SIZE = 16 EPOCHS = 50 DEVICE = torch.device('cuda:0' if torch.cuda.is_available() else 'cpu') use_amp = True use_dp = True classes = 7 resume = None CLIP_GRAD = 5.0 Best_ACC = 0 #记录最高得分 use_ema=True model_ema_decay=0.9998 start_epoch=1 seed=1 seed_everything(seed) # 数据增强 mixup mixup_fn = Mixup( mixup_alpha=0.8, cutmix_alpha=1.0, cutmix_minmax=None, prob=0.1, switch_prob=0.5, mode='batch', label_smoothing=0.1, num_classes=classes) # 读取数据集 dataset_train = datasets.ImageFolder('/home/adminis/hpy/ConvNextV2_Demo/RAF-DB/RAF/train', transform=transform) dataset_test = datasets.ImageFolder("/home/adminis/hpy/ConvNextV2_Demo/RAF-DB/RAF/valid", transform=transform_test) 帮我用pytorch实现模型在模型训练中使用LDAM损失函数

好的，下面是使用LDAM损失函数训练模型的代码：

import torch.optim as optim
from torch.optim.lr_scheduler import CosineAnnealingLR
from torch.utils.data import DataLoader

# 定义LDAM损失函数
class LDAMLoss(nn.Module):
    def __init__(self, cls_num_list, max_m=0.5, weight=None, s=30):
        super(LDAMLoss, self).__init__()
        m_list = 1.0 / np.sqrt(np.sqrt(cls_num_list))
        m_list = m_list * (max_m / np.max(m_list))
        m_list = torch.cuda.FloatTensor(m_list)
        self.m_list = m_list
        assert s > 0
        self.s = s
        if weight is not None:
            weight = torch.FloatTensor(weight).cuda()
        self.weight = weight
        self.cls_num_list = cls_num_list

    def forward(self, x, target):
        index = torch.zeros_like(x, dtype=torch.uint8)
        index_float = index.type(torch.cuda.FloatTensor)
        batch_m = torch.matmul(self.m_list[None, :], index_float.transpose(1,0)) # 0,1
        batch_m = batch_m.view((x.size(0), 1)) # size=(batch_size, 1)
        x_m = x - batch_m
        output = torch.where(index, x_m, x)
        if self.weight is not None:
            output = output * self.weight[None, :]
        target = torch.flatten(target) # 将 target 转换成 1D Tensor
        logit = output * self.s
        return F.cross_entropy(logit, target, weight=self.weight)

# 定义模型
model = models.resnet18(pretrained=True)
num_ftrs = model.fc.in_features
model.fc = nn.Linear(num_ftrs, classes)
model.to(DEVICE)

# 定义优化器和学习率调整器
optimizer = optim.Adam(model.parameters(), lr=model_lr)
scheduler = CosineAnnealingLR(optimizer, T_max=EPOCHS, eta_min=1e-6)

# 定义LDAM损失函数
cls_num_list = [len(dataset_train[dataset_train.targets == t]) for t in range(classes)]
criterion = LDAMLoss(cls_num_list)

# 定义数据加载器
train_loader = DataLoader(dataset_train, batch_size=BATCH_SIZE, shuffle=True, num_workers=4, pin_memory=True)
test_loader = DataLoader(dataset_test, batch_size=BATCH_SIZE, shuffle=False, num_workers=4, pin_memory=True)

# 训练模型
best_acc = 0.0
for epoch in range(start_epoch, EPOCHS + 1):
    model.train()
    train_loss = 0.0
    train_corrects = 0
    for inputs, labels in train_loader:
        inputs, labels = inputs.to(DEVICE), labels.to(DEVICE)
        if use_dp:
            inputs, labels = dp(inputs, labels)
        if use_amp:
            with amp.autocast():
                inputs, labels = mixup_fn(inputs, labels)
                outputs = model(inputs)
                loss = criterion(outputs, labels)
            scaler.scale(loss).backward()
            scaler.unscale_(optimizer)
            torch.nn.utils.clip_grad_norm_(model.parameters(), CLIP_GRAD)
            scaler.step(optimizer)
            scaler.update()
        else:
            inputs, labels_a, labels_b, lam = mixup_fn(inputs, labels)
            outputs = model(inputs)
            loss = mixup_criterion(criterion, outputs, labels_a, labels_b, lam)
            loss.backward()
            torch.nn.utils.clip_grad_norm_(model.parameters(), CLIP_GRAD)
            optimizer.step()
            optimizer.zero_grad()
        train_loss += loss.item() * inputs.size(0)
        _, preds = torch.max(outputs, 1)
        train_corrects += torch.sum(preds == labels.data)
    train_loss /= len(dataset_train)
    train_acc = train_corrects.double() / len(dataset_train)

    model.eval()
    test_loss = 0.0
    test_corrects = 0
    with torch.no_grad():
        for inputs, labels in test_loader:
            inputs, labels = inputs.to(DEVICE), labels.to(DEVICE)
            outputs = model(inputs)
            loss = criterion(outputs, labels)
            test_loss += loss.item() * inputs.size(0)
            _, preds = torch.max(outputs, 1)
            test_corrects += torch.sum(preds == labels.data)
    test_loss /= len(dataset_test)
    test_acc = test_corrects.double() / len(dataset_test)

    # 更新最佳模型
    if test_acc > best_acc:
        if use_ema:
            ema_model.load_state_dict(model.state_dict())
        best_acc = test_acc

    # 更新学习率
    scheduler.step()

    # 打印训练结果
    print('Epoch [{}/{}], Train Loss: {:.4f}, Train Acc: {:.4f}, Test Loss: {:.4f}, Test Acc: {:.4f}'.format(
        epoch, EPOCHS, train_loss, train_acc, test_loss, test_acc))

Pytorch中怎么使用vis.line 来画train_loss train_acc test_acc 这三条线在同一个图中 并给出一个在深度学习中以网络为resnet50 、数据集为cifar10、把输出的模型保存、输出的数据保存到csv文件中、把代码模块化的实战代码

首先，我们需要安装visdom库，可以使用以下命令：

!pip install visdom

接下来，需要在代码中引入相关库和模块：

import torch
import torch.nn as nn
import torch.optim as optim
import torchvision
import torchvision.transforms as transforms
import visdom
import csv

然后，定义一个函数来加载数据集：

def load_dataset():
    transform_train = transforms.Compose(
        [transforms.RandomCrop(32, padding=4),
         transforms.RandomHorizontalFlip(),
         transforms.ToTensor(),
         transforms.Normalize((0.5, 0.5, 0.5), (0.5, 0.5, 0.5))])

    transform_test = transforms.Compose(
        [transforms.ToTensor(),
         transforms.Normalize((0.5, 0.5, 0.5), (0.5, 0.5, 0.5))])

    trainset = torchvision.datasets.CIFAR10(root='./data', train=True,
                                            download=True, transform=transform_train)
    trainloader = torch.utils.data.DataLoader(trainset, batch_size=128,
                                              shuffle=True, num_workers=2)

    testset = torchvision.datasets.CIFAR10(root='./data', train=False,
                                           download=True, transform=transform_test)
    testloader = torch.utils.data.DataLoader(testset, batch_size=128,
                                             shuffle=False, num_workers=2)

    classes = ('plane', 'car', 'bird', 'cat',
               'deer', 'dog', 'frog', 'horse', 'ship', 'truck')

    return trainloader, testloader

接下来，定义一个函数来构建ResNet50网络：

class ResNet50(nn.Module):
    def __init__(self, num_classes=10):
        super(ResNet50, self).__init__()
        self.resnet50 = torchvision.models.resnet50(pretrained=False)
        num_ftrs = self.resnet50.fc.in_features
        self.resnet50.fc = nn.Linear(num_ftrs, num_classes)

    def forward(self, x):
        x = self.resnet50(x)
        return x

然后，定义一个函数来训练模型：

def train(model, trainloader, criterion, optimizer, epoch, device, vis):
    model.train()
    train_loss = 0.0
    correct = 0
    total = 0
    for batch_idx, (inputs, targets) in enumerate(trainloader):
        inputs, targets = inputs.to(device), targets.to(device)
        optimizer.zero_grad()
        outputs = model(inputs)
        loss = criterion(outputs, targets)
        loss.backward()
        optimizer.step()

        train_loss += loss.item()
        _, predicted = outputs.max(1)
        total += targets.size(0)
        correct += predicted.eq(targets).sum().item()

        if batch_idx % 10 == 0:
            vis.line(X=torch.Tensor([epoch+batch_idx/len(trainloader)]), Y=torch.Tensor([train_loss/len(trainloader)]), win='train_loss', update='append', name='train_loss')
            vis.line(X=torch.Tensor([epoch+batch_idx/len(trainloader)]), Y=torch.Tensor([100.*correct/total]), win='train_acc', update='append', name='train_acc')

    print('Train Epoch: {} Loss: {:.6f} Acc: {:.6f}'.format(
        epoch, train_loss/len(trainloader), 100.*correct/total))

接下来，定义一个函数来测试模型：

def test(model, testloader, criterion, epoch, device, vis):
    model.eval()
    test_loss = 0.0
    correct = 0
    total = 0
    with torch.no_grad():
        for batch_idx, (inputs, targets) in enumerate(testloader):
            inputs, targets = inputs.to(device), targets.to(device)
            outputs = model(inputs)
            loss = criterion(outputs, targets)

            test_loss += loss.item()
            _, predicted = outputs.max(1)
            total += targets.size(0)
            correct += predicted.eq(targets).sum().item()

            if batch_idx % 10 == 0:
                vis.line(X=torch.Tensor([epoch+batch_idx/len(testloader)]), Y=torch.Tensor([100.*correct/total]), win='test_acc', update='append', name='test_acc')

    print('Test Epoch: {} Loss: {:.6f} Acc: {:.6f}'.format(
        epoch, test_loss/len(testloader), 100.*correct/total))

接下来，定义主函数来调用以上函数：

def main():
    vis = visdom.Visdom()
    device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
    trainloader, testloader = load_dataset()
    model = ResNet50().to(device)
    criterion = nn.CrossEntropyLoss()
    optimizer = optim.SGD(model.parameters(), lr=0.1, momentum=0.9, weight_decay=5e-4)

    for epoch in range(100):
        train(model, trainloader, criterion, optimizer, epoch, device, vis)
        test(model, testloader, criterion, epoch, device, vis)

    torch.save(model.state_dict(), 'resnet50_cifar10.pth')

    with open('output.csv', mode='w') as file:
        writer = csv.writer(file)
        writer.writerow(['epoch', 'train_loss', 'train_acc', 'test_acc'])
        for epoch in range(100):
            train_loss = vis.line(Y=torch.Tensor([0]), win='train_loss', name='train_loss', update='none')
            train_acc = vis.line(Y=torch.Tensor([0]), win='train_acc', name='train_acc', update='none')
            test_acc = vis.line(Y=torch.Tensor([0]), win='test_acc', name='test_acc', update='none')
            writer.writerow([epoch+1, train_loss['Y'][-1], train_acc['Y'][-1], test_acc['Y'][-1]])

最后，运行主函数即可进行训练、测试、模型保存和输出数据到csv文件的操作：

if __name__ == '__main__':
    main()

完整代码如下：