Few-shot learning aims to learn a new concept when only a few training examples are available, which has been extensively explored in recent years. However, most of the current works heavily rely on a large-scale labeled auxiliary set to train their models in an episodic-training paradigm. Such a kind of supervised setting basically limits the widespread use of few-shot learning algorithms, especially in real-world applications. Instead, in this paper, we develop a novel framework called \emph{Unsupervised Few-shot Learning via Distribution Shift-based Data Augmentation} (ULDA), which pays attention to the distribution diversity inside each constructed pretext few-shot task when using data augmentation. Importantly, we highlight the value and importance of the distribution diversity in the augmentation-based pretext few-shot tasks. In ULDA, we systemically investigate the effects of different augmentation techniques and propose to strengthen the distribution diversity (or difference) between the query set and support set in each few-shot task, by augmenting these two sets separately (i.e. shifting). In this way, even incorporated with simple augmentation techniques (e.g. random crop, color jittering, or rotation), our ULDA can produce a significant improvement. In the experiments, few-shot models learned by ULDA can achieve superior generalization performance and obtain state-of-the-art results in a variety of established few-shot learning tasks on \emph{mini}ImageNet and \emph{tiered}ImageNet. %The code will be released soon. The source code is available in \textcolor{blue}{\emph{https://github.com/WonderSeven/ULDA}}.

本文提出了一种名为ULDA的无监督少样本学习框架，通过数据增强中的分布偏移建立预文本少样本任务，重视分布多样性，扩展训练而实现良好的泛化性能并获得了既定少样本学习任务中的最新结果。

多样性帮助：基于分布偏移的数据增强实现无监督少样本学习