深度学习：UserWarning: The parameter ‘pretrained‘ is deprecated since 0.13..解决办法

深度学习：UserWarning: The parameter 'pretrained' is deprecated since 0.13 and may be removed in the future, please use 'weights' instead. 解决办法

1 报错警告：

pytorch版本：0.14.1

在利用pytorch中的预训练模型时，如resnet18

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import torchvision.models as models
pretrained_model = models.resnet18(pretrained=True)

会提示警告：

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UserWarning: The parameter 'pretrained' is deprecated since 0.13 and may be removed in the future, please use 'weights' instead.
  f"The parameter '{pretrained_param}' is deprecated since 0.13 and may be removed in the future, "

看出给出的原因是在0.13版本后，开始使用weights参数。

2 处理方法：

接下来为处理这个问题的方法，不同的预训练模型方法适用以model.resnet18()为例

首先点击models.resnet18()函数，进入函数内部，可以看到如下内容

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@handle_legacy_interface(weights=("pretrained", ResNet18_Weights.IMAGENET1K_V1))

def resnet18(*, weights: Optional[ResNet18_Weights] = None, progress: bool = True, **kwargs: Any) -> ResNet:
"""ResNet-18 from Deep Residual Learning for Image Recognition <https://arxiv.org/pdf/1512.03385.pdf>__.

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  Args:
      weights (:class:`~torchvision.models.ResNet18_Weights`, optional): The
          pretrained weights to use. See
          :class:`~torchvision.models.ResNet18_Weights` below for
          more details, and possible values. By default, no pre-trained
          weights are used.
      progress (bool, optional): If True, displays a progress bar of the
          download to stderr. Default is True.
      **kwargs: parameters passed to the ``torchvision.models.resnet.ResNet``
          base class. Please refer to the `source code
          <https://github.com/pytorch/vision/blob/main/torchvision/models/resnet.py>`_
          for more details about this class.

  .. autoclass:: torchvision.models.ResNet18_Weights
      :members:
  """
  weights = ResNet18_Weights.verify(weights)

  return _resnet(BasicBlock, [2, 2, 2, 2], weights, progress, **kwargs)

首先看到第一行weights=("pretrained", ResNet18_Weights.IMAGENET1K_V1)，所以这个还是可以用的，相当于利用了ResNet18_Weights.IMAGENET1K_V1参数。然后看第二行的这个weights函数接受的ResNet18_Weights,再次进入内部，可以看到如下：

class ResNet18_Weights(WeightsEnum):
IMAGENET1K_V1 = Weights(
url="https://download.pytorch.org/models/resnet18-f37072fd.pth",
transforms=partial(ImageClassification, crop_size=224),
meta={
**_COMMON_META,
"num_params": 11689512,
"recipe": "https://github.com/pytorch/vision/tree/main/references/classification#resnet",
"_metrics": {
"ImageNet-1K": {
"acc@1": 69.758,
"acc@5": 89.078,
}
},
"_docs": """These weights reproduce closely the results of the paper using a simple training recipe.""",
},
)
DEFAULT = IMAGENET1K_V1

这个是选择的参数，其他的预训练模型可以有多个版本，如下面ResNet50_Weights, 可以根据自己需求选择需要的。

上面的函数已经给出了调用方法Args: weights (:class:~torchvision.models.ResNet18_Weights, optional)
所以直接

pretrained_model = models.resnet18(models.ResNet18_Weights.IMAGENET1K_V1)

也可以

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pretrained_model = models.resnet18(models.ResNet18_Weights.DEFAULT)

这两个是一样的。

3.总结

在版本更新之后可能会有些变化，有些函数调用方式的变化可以直接通过函数内部查看然后修改，重点是修改思路解决相同类似的问题。