torch.load加载权重时报错 Magic Number Error

有时候使用 torch.load 加载比较古老的权重文件时可能报错 Magic Number Error，这有可能是因为该文件使用 pickle 存储并且编码使用了 latin1，此时可以这样加载：

def resnet50(weights_path=None, **kwargs):
    """Constructs a ResNet-50 model.
    """
    model = ResNet(Bottleneck, [3, 4, 6, 3], **kwargs)
    if weights_path:
        import pickle
        with open(weights_path, 'rb') as f:
            obj = f.read()
        weights = {key: weight_dict for key, weight_dict in pickle.loads(obj, encoding='latin1').items()}
        model.load_state_dict(weights)
    return model

参考：

https://github.com/cydonia999/VGGFace2-pytorch/issues/2#issuecomment-463571389