图像分割实战-系列教程5：unet医学细胞分割实战3（医学数据集、图像分割、语义分割、unet网络、代码逐行解读）

🍁🍁🍁图像分割实战-系列教程 总目录

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本篇文章的代码运行界面均在Pycharm中进行
本篇文章配套的代码资源已经上传

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unet医学细胞分割实战2
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unet医学细胞分割实战4

6、训练主函数解析

6.1 读取配置文件

def main():
    config = vars(parse_args())
    if config['name'] is None:
        if config['deep_supervision']:
            config['name'] = '%s_%s_wDS' % (config['dataset'], config['arch'])
        else:
            config['name'] = '%s_%s_woDS' % (config['dataset'], config['arch'])
    os.makedirs('models/%s' % config['name'], exist_ok=True)
    print('-' * 20)
    for key in config:
        print('%s: %s' % (key, config[key]))
    print('-' * 20)
    with open('models/%s/config.yml' % config['name'], 'w') as f:
        yaml.dump(config, f)

1. main函数
2. 解析命令行参数为字典
3. 检查 config[‘name’] 是否为 None。如果是
4. 它根据 config[‘deep_supervision’] 的布尔值来设置 config[‘name’]， 如果config[‘deep_supervision’] 的值为True
5. config[‘dataset’] 和 config[‘arch’] 的值，并在末尾添加 ‘_wDS’（表示“with Deep Supervision”）
6. 如果为False，末尾则添加 ‘_woDS’（表示“without Deep Supervision”）
7. 使用 config[‘name’] 来创建一个新目录。这个目录位于 ‘models/’ 目录下，目录名是 config[‘name’] 的值，exist_ok=True 参数的意思是如果目录已经存在，则不会抛出错误
8. 打印符号
9. 打印所有配置参数的名字和默认值
   10.打印符号

5.2 损失函数

    # define loss function (criterion)
    if config['loss'] == 'BCEWithLogitsLoss':
        criterion = nn.BCEWithLogitsLoss().cuda()#WithLogits 就是先将输出结果经过sigmoid再交叉熵
    else:
        criterion = losses.__dict__[config['loss']]().cuda()

    cudnn.benchmark = True

    # create model
    print("=> creating model %s" % config['arch'])
    model = archs.__dict__[config['arch']](config['num_classes'],
                                           config['input_channels'],
                                           config['deep_supervision'])

    model = model.cuda()

    params = filter(lambda p: p.requires_grad, model.parameters())
    if config['optimizer'] == 'Adam':
        optimizer = optim.Adam(
            params, lr=config['lr'], weight_decay=config['weight_decay'])
    elif config['optimizer'] == 'SGD':
        optimizer = optim.SGD(params, lr=config['lr'], momentum=config['momentum'],
                              nesterov=config['nesterov'], weight_decay=config['weight_decay'])
    else:
        raise NotImplementedError

    if config['scheduler'] == 'CosineAnnealingLR':
        scheduler = lr_scheduler.CosineAnnealingLR(
            optimizer, T_max=config['epochs'], eta_min=config['min_lr'])
    elif config['scheduler'] == 'ReduceLROnPlateau':
        scheduler = lr_scheduler.ReduceLROnPlateau(optimizer, factor=config['factor'], patience=config['patience'],
                                                   verbose=1, min_lr=config['min_lr'])
    elif config['scheduler'] == 'MultiStepLR':
        scheduler = lr_scheduler.MultiStepLR(optimizer, milestones=[int(e) for e in config['milestones'].split(',')], gamma=config['gamma'])
    elif config['scheduler'] == 'ConstantLR':
        scheduler = None
    else:
        raise NotImplementedError

    # Data loading code
    img_ids = glob(os.path.join('inputs', config['dataset'], 'images', '*' + config['img_ext']))
    img_ids = [os.path.splitext(os.path.basename(p))[0] for p in img_ids]

    train_img_ids, val_img_ids = train_test_split(img_ids, test_size=0.2, random_state=41)

5.3 数据集制作

    #数据增强：
    train_transform = Compose([
        transforms.RandomRotate90(),
        transforms.Flip(),
        OneOf([
            transforms.HueSaturationValue(),
            transforms.RandomBrightness(),
            transforms.RandomContrast(),
        ], p=1),#按照归一化的概率选择执行哪一个
        transforms.Resize(config['input_h'], config['input_w']),
        transforms.Normalize(),
    ])

    val_transform = Compose([
        transforms.Resize(config['input_h'], config['input_w']),
        transforms.Normalize(),
    ])

    train_dataset = Dataset(
        img_ids=train_img_ids,
        img_dir=os.path.join('inputs', config['dataset'], 'images'),
        mask_dir=os.path.join('inputs', config['dataset'], 'masks'),
        img_ext=config['img_ext'],
        mask_ext=config['mask_ext'],
        num_classes=config['num_classes'],
        transform=train_transform)
    val_dataset = Dataset(
        img_ids=val_img_ids,
        img_dir=os.path.join('inputs', config['dataset'], 'images'),
        mask_dir=os.path.join('inputs', config['dataset'], 'masks'),
        img_ext=config['img_ext'],
        mask_ext=config['mask_ext'],
        num_classes=config['num_classes'],
        transform=val_transform)

    train_loader = torch.utils.data.DataLoader(
        train_dataset,
        batch_size=config['batch_size'],
        shuffle=True,
        num_workers=config['num_workers'],
        drop_last=True)#不能整除的batch是否就不要了
    val_loader = torch.utils.data.DataLoader(
        val_dataset,
        batch_size=config['batch_size'],
        shuffle=False,
        num_workers=config['num_workers'],
        drop_last=False)

    log = OrderedDict([
        ('epoch', []),
        ('lr', []),
        ('loss', []),
        ('iou', []),
        ('val_loss', []),
        ('val_iou', []),
    ])

5.4 迭代训练

    best_iou = 0
    trigger = 0
    for epoch in range(config['epochs']):
        print('Epoch [%d/%d]' % (epoch, config['epochs']))

        # train for one epoch
        train_log = train(config, train_loader, model, criterion, optimizer)
        # evaluate on validation set
        val_log = validate(config, val_loader, model, criterion)

        if config['scheduler'] == 'CosineAnnealingLR':
            scheduler.step()
        elif config['scheduler'] == 'ReduceLROnPlateau':
            scheduler.step(val_log['loss'])

        print('loss %.4f - iou %.4f - val_loss %.4f - val_iou %.4f'
              % (train_log['loss'], train_log['iou'], val_log['loss'], val_log['iou']))

        log['epoch'].append(epoch)
        log['lr'].append(config['lr'])
        log['loss'].append(train_log['loss'])
        log['iou'].append(train_log['iou'])
        log['val_loss'].append(val_log['loss'])
        log['val_iou'].append(val_log['iou'])

        pd.DataFrame(log).to_csv('models/%s/log.csv' %
                                 config['name'], index=False)

        trigger += 1

        if val_log['iou'] > best_iou:
            torch.save(model.state_dict(), 'models/%s/model.pth' %
                       config['name'])
            best_iou = val_log['iou']
            print("=> saved best model")
            trigger = 0

        # early stopping
        if config['early_stopping'] >= 0 and trigger >= config['early_stopping']:
            print("=> early stopping")
            break

        torch.cuda.empty_cache()

上篇内容：
unet医学细胞分割实战2
下篇内容：
unet医学细胞分割实战4