元学习示例：maml_miniimagenet无法下载数据的解决办法

        在learn2learn库中，有一个示例：maml_miniimagenet.py。在运行该示例时，总是不能下载到miniimagenet数据，这里可以直接从源码中找到下载链接。源码文件为learn2learn/vision/datasets/mini_imagenet.py。具体代码部分如下

    def __init__(self,root,mode='train',transform=None,target_transform=None,download=False,):super(MiniImagenet, self).__init__()self.root = os.path.expanduser(root)if not os.path.exists(self.root):os.mkdir(self.root)self.transform = transformself.target_transform = target_transformself.mode = modeself._bookkeeping_path = os.path.join(self.root, 'mini-imagenet-bookkeeping-' + mode + '.pkl')if self.mode == 'test':google_drive_file_id = '1wpmY-hmiJUUlRBkO9ZDCXAcIpHEFdOhD'dropbox_file_link = 'https://www.dropbox.com/s/ye9jeb5tyz0x01b/mini-imagenet-cache-test.pkl?dl=1'zenodo_file_link = 'https://zenodo.org/record/7978538/files/mini-imagenet-cache-test.pkl'elif self.mode == 'train':google_drive_file_id = '1I3itTXpXxGV68olxM5roceUMG8itH9Xj'dropbox_file_link = 'https://www.dropbox.com/s/9g8c6w345s2ek03/mini-imagenet-cache-train.pkl?dl=1'zenodo_file_link = 'https://zenodo.org/record/7978538/files/mini-imagenet-cache-train.pkl'elif self.mode == 'validation':google_drive_file_id = '1KY5e491bkLFqJDp0-UWou3463Mo8AOco'dropbox_file_link = 'https://www.dropbox.com/s/ip1b7se3gij3r1b/mini-imagenet-cache-validation.pkl?dl=1'zenodo_file_link = 'https://zenodo.org/record/7978538/files/mini-imagenet-cache-validation.pkl'else:raise ValueError('Needs to be train, test or validation')pickle_file = os.path.join(self.root, 'mini-imagenet-cache-' + mode + '.pkl')try:if not self._check_exists() and download:print('Downloading mini-ImageNet --', mode)download_file(dropbox_file_link, pickle_file)with open(pickle_file, 'rb') as f:self.data = pickle.load(f)except Exception:try:if not self._check_exists() and download:print('Downloading mini-ImageNet --', mode)download_pkl(google_drive_file_id, self.root, mode)with open(pickle_file, 'rb') as f:self.data = pickle.load(f)except pickle.UnpicklingError:if not self._check_exists() and download:print('Download failed. Re-trying mini-ImageNet --', mode)download_file(dropbox_file_link, pickle_file)with open(pickle_file, 'rb') as f:self.data = pickle.load(f)self.x = torch.from_numpy(self.data["image_data"]).permute(0, 3, 1, 2).float()self.y = np.ones(len(self.x))# TODO Remove index_classes from hereself.class_idx = index_classes(self.data['class_dict'].keys())for class_name, idxs in self.data['class_dict'].items():for idx in idxs:self.y[idx] = self.class_idx[class_name]

        从上边的代码中可以发现，learn2learn一共提供了三种下载地址，但实际上我们国内所能访问的只有最后一种zenodo，至少在我的电脑上google drive和drop box都是无法连接的。而learn2learn下载部分的代码其实没有使用zemodo这个地址，只是使用了前两种，导致运行程序时不会自动的下载数据。

        解决办法很简单，就是直接将zenodo开头的这三个地址直接复制到浏览器中，就可以将train,validation,test这三个pkl文件下载到了。将下载好的文件放到home/data路径下，那么再次运行程序的时候就不需要下载了，就可以开心的进行训练了！