Positive Unlabeled Contrastive Learning
- URL: http://arxiv.org/abs/2206.01206v3
- Date: Thu, 28 Mar 2024 23:25:14 GMT
- Title: Positive Unlabeled Contrastive Learning
- Authors: Anish Acharya, Sujay Sanghavi, Li Jing, Bhargav Bhushanam, Dhruv Choudhary, Michael Rabbat, Inderjit Dhillon,
- Abstract summary: We extend the self-supervised pretraining paradigm to the classical positive unlabeled (PU) setting.
We develop a simple methodology to pseudo-label the unlabeled samples using a new PU-specific clustering scheme.
Our method handily outperforms state-of-the-art PU methods over several standard PU benchmark datasets.
- Score: 14.975173394072053
- License: http://creativecommons.org/licenses/by-nc-sa/4.0/
- Abstract: Self-supervised pretraining on unlabeled data followed by supervised fine-tuning on labeled data is a popular paradigm for learning from limited labeled examples. We extend this paradigm to the classical positive unlabeled (PU) setting, where the task is to learn a binary classifier given only a few labeled positive samples, and (often) a large amount of unlabeled samples (which could be positive or negative). We first propose a simple extension of standard infoNCE family of contrastive losses, to the PU setting; and show that this learns superior representations, as compared to existing unsupervised and supervised approaches. We then develop a simple methodology to pseudo-label the unlabeled samples using a new PU-specific clustering scheme; these pseudo-labels can then be used to train the final (positive vs. negative) classifier. Our method handily outperforms state-of-the-art PU methods over several standard PU benchmark datasets, while not requiring a-priori knowledge of any class prior (which is a common assumption in other PU methods). We also provide a simple theoretical analysis that motivates our methods.
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