torch.load加載權重時報錯 Magic Number Error

有時候使用 torch.load 加載比較古老的權重文件時可能報錯 Magic Number Error，這有可能是因為該文件使用 pickle 存儲並且編碼使用了 latin1，此時可以這樣加載：

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

參考：

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