基于pytorch环境用arcface训练模型的代码

以下是基于PyTorch环境使用ArcFace训练模型的代码：

import torch
import torch.nn as nn
import torch.nn.functional as F
from torch.utils.data import DataLoader
from torchvision import datasets, transforms
import argparse
from tqdm import tqdm
import math

# 定义模型
class ArcFace(nn.Module):
    def __init__(self, num_classes=10, emb_size=2):
        super(ArcFace, self).__init__()
        self.num_classes = num_classes
        self.emb_size = emb_size

        self.features = nn.Sequential(
            nn.Conv2d(1, 16, kernel_size=3, stride=1, padding=1),
            nn.BatchNorm2d(16),
            nn.ReLU(inplace=True),
            nn.MaxPool2d(kernel_size=2, stride=2),

            nn.Conv2d(16, 32, kernel_size=3, stride=1, padding=1),
            nn.BatchNorm2d(32),
            nn.ReLU(inplace=True),
            nn.MaxPool2d(kernel_size=2, stride=2),

            nn.Conv2d(32, 64, kernel_size=3, stride=1, padding=1),
            nn.BatchNorm2d(64),
            nn.ReLU(inplace=True),
            nn.MaxPool2d(kernel_size=2, stride=2),

            nn.Conv2d(64, 128, kernel_size=3, stride=1, padding=1),
            nn.BatchNorm2d(128),
            nn.ReLU(inplace=True),
            nn.MaxPool2d(kernel_size=2, stride=2),
        )

        self.avgpool = nn.AdaptiveAvgPool2d((1, 1))
        self.fc = nn.Linear(128, emb_size, bias=False)
        self.classifier = nn.Linear(emb_size, num_classes, bias=False)

    def forward(self, x, label=None):
        x = self.features(x)
        x = self.avgpool(x)
        x = x.view(x.size(0), -1)

        x = self.fc(x)

        if label is not None:
            # 计算cos(theta)
            cosine = F.linear(F.normalize(x), F.normalize(self.classifier.weight))
            # 计算theta
            theta = torch.acos(torch.clamp(cosine, -1.0 + 1e-7, 1.0 - 1e-7))
            # 计算one-hot编码
            one_hot = torch.zeros_like(cosine)
            one_hot.scatter_(1, label.view(-1, 1).long(), 1)
            # 计算计算cos(theta + m)
            new_cosine = torch.cos(theta + 0.1)
            # 计算cos(theta + m)与one-hot编码的乘积
            output = new_cosine * cosine - one_hot * (new_cosine - cosine)
        else:
            output = self.classifier(x)

        return output


# 定义训练方法
def train(model, device, train_loader, optimizer, epoch, log_interval):
    model.train()
    train_loss = 0
    correct = 0
    total = 0

    pbar = tqdm(train_loader)
    for batch_idx, (data, labels) in enumerate(pbar):
        data, labels = data.to(device), labels.to(device)
        optimizer.zero_grad()
        output = model(data, labels)
        loss = F.cross_entropy(output, labels)
        loss.backward()
        optimizer.step()

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

        pbar.set_description('Train epoch {} Loss: {:.6f} Acc: {:.4f}'.format(
            epoch, train_loss / (batch_idx + 1), 100. * correct / total))

        # 打印日志
        if batch_idx % log_interval == 0:
            print('Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f} Acc: {:.4f}'.format(
                epoch, batch_idx * len(data), len(train_loader.dataset),
                100. * batch_idx / len(train_loader), loss.item(), 100. * correct / total))


# 定义测试方法
def test(model, device, test_loader):
    model.eval()
    test_loss = 0
    correct = 0
    with torch.no_grad():
        for data, labels in test_loader:
            data, labels = data.to(device), labels.to(device)
            output = model(data)
            test_loss += F.cross_entropy(output, labels, reduction='sum').item()

            _, predicted = output.max(1)
            correct += predicted.eq(labels).sum().item()

    test_loss /= len(test_loader.dataset)

    print('\nTest set: Average loss: {:.4f}, Accuracy: {}/{} ({:.0f}%)\n'.format(
        test_loss, correct, len(test_loader.dataset),
        100. * correct / len(test_loader.dataset)))


def main():
    # 解析参数
    parser = argparse.ArgumentParser(description='PyTorch ArcFace Example')
    parser.add_argument('--batch-size', type=int, default=128, metavar='N',
                        help='input batch size for training (default: 128)')
    parser.add_argument('--test-batch-size', type=int, default=128, metavar='N',
                        help='input batch size for testing (default: 128)')
    parser.add_argument('--epochs', type=int, default=10, metavar='N',
                        help='number of epochs to train (default: 10)')
    parser.add_argument('--lr', type=float, default=0.1, metavar='LR',
                        help='learning rate (default: 0.1)')
    parser.add_argument('--momentum', type=float, default=0.9, metavar='M',
                        help='SGD momentum (default: 0.9)')
    parser.add_argument('--no-cuda', action='store_true', default=False,
                        help='disables CUDA training')
    parser.add_argument('--seed', type=int, default=1, metavar='S',
                        help='random seed (default: 1)')
    parser.add_argument('--log-interval', type=int, default=10, metavar='N',
                        help='how many batches to wait before logging training status')
    parser.add_argument('--save-model', action='store_true', default=False,
                        help='Save the trained model')
    args = parser.parse_args()

    # 判断是否使用GPU
    use_cuda = not args.no_cuda and torch.cuda.is_available()
    torch.manual_seed(args.seed)
    device = torch.device('cuda' if use_cuda else 'cpu')

    # 加载数据
    kwargs = {'num_workers': 1, 'pin_memory': True} if use_cuda else {}
    transform = transforms.Compose([
        transforms.ToTensor(),
        transforms.Normalize((0.1307,), (0.3081,))
    ])
    train_dataset = datasets.MNIST('../data', train=True, download=True,
                                   transform=transform)
    test_dataset = datasets.MNIST('../data', train=False,
                                  transform=transform)
    train_loader = DataLoader(train_dataset, batch_size=args.batch_size, shuffle=True, **kwargs)
    test_loader = DataLoader(test_dataset, batch_size=args.test_batch_size, shuffle=True, **kwargs)

    # 初始化模型
    model = ArcFace(num_classes=10, emb_size=2).to(device)
    optimizer = torch.optim.SGD(model.parameters(), lr=args.lr, momentum=args.momentum)

    # 训练模型
    for epoch in range(1, args.epochs + 1):
        train(model, device, train_loader, optimizer, epoch, args.log_interval)
        test(model, device, test_loader)

        # 保存模型
        if args.save_model:
            torch.save(model.state_dict(), 'arcface_mnist.pt')


if __name__ == '__main__':
    main()

注意，这里的模型是使用MNIST数据集进行训练的，如果需要使用其他数据集，可以根据需要更改数据集的加载方式。同时，这里的代码只是一个示例，实际使用时还需要根据具体情况进行修改。