DeepDPM: Deep Clustering With an Unknown Number of Clusters

TL;DR

DeepDPM introduces a deep clustering method that dynamically infers the number of clusters during training, eliminating the need for predefined K and outperforming existing methods, including on large-scale datasets like ImageNet.

Contribution

It proposes a novel deep clustering approach that infers the number of clusters during training using a split/merge framework and a new loss, addressing a key limitation of existing methods.

Findings

Outperforms existing nonparametric deep clustering methods.

First to evaluate deep nonparametric clustering on ImageNet.

Demonstrates the importance of inferring K for imbalanced datasets.

Abstract

Deep Learning (DL) has shown great promise in the unsupervised task of clustering. That said, while in classical (i.e., non-deep) clustering the benefits of the nonparametric approach are well known, most deep-clustering methods are parametric: namely, they require a predefined and fixed number of clusters, denoted by K. When K is unknown, however, using model-selection criteria to choose its optimal value might become computationally expensive, especially in DL as the training process would have to be repeated numerous times. In this work, we bridge this gap by introducing an effective deep-clustering method that does not require knowing the value of K as it infers it during the learning. Using a split/merge framework, a dynamic architecture that adapts to the changing K, and a novel loss, our proposed method outperforms existing nonparametric methods (both classical and deep ones). While the very few existing deep nonparametric methods lack scalability, we demonstrate ours by being the first to report the performance of such a method on ImageNet. We also demonstrate the importance of inferring K by showing how methods that fix it deteriorate in performance when their assumed K value gets further from the ground-truth one, especially on imbalanced datasets. Our code is available at https://github.com/BGU-CS-VIL/DeepDPM.