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arXiv · 1906.07413

Learning Imbalanced Datasets with Label-Distribution-Aware Margin Loss

Kaidi Cao·Colin Wei·Adrien Gaidon·Nikos Arechiga·Tengyu Ma
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Abstract

Deep learning algorithms can fare poorly when the training dataset suffers from heavy class-imbalance but the testing criterion requires good generalization on less frequent classes. We design two novel methods to improve performance in such scenarios. First, we propose a theoretically-principled label-distribution-aware margin (LDAM) loss motivated by minimizing a margin-based generalization bound. This loss replaces the standard cross-entropy objective during training and can be applied with prior strategies for training with class-imbalance such as re-weighting or re-sampling. Second, we propose a simple, yet effective, training schedule that defers re-weighting until after the initial stage, allowing the model to learn an initial representation while avoiding some of the complications associated with re-weighting or re-sampling. We test our methods on several benchmark vision tasks including the real-world imbalanced dataset iNaturalist 2018. Our experiments show that either of these methods alone can already improve over existing techniques and their combination achieves even better performance gains.

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Kaidi Cao, Colin Wei, Adrien Gaidon, Nikos Arechiga, Tengyu Ma. 2019-10-27. Learning Imbalanced Datasets with Label-Distribution-Aware Margin Loss. https://arxiv.org/abs/1906.07413

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