SPOT: A framework for selection of prototypes using optimal transport

TL;DR

This paper introduces SPOT, an optimal transport-based framework for selecting representative prototypes that efficiently summarize datasets, aiding interpretability and decision-making in machine learning applications.

Contribution

The paper presents a novel OT-based method for prototype selection that leverages submodularity and greedy algorithms for efficient and effective data summarization.

Findings

Outperforms existing methods on real-world benchmarks.

Provides a fast, deterministic approximation algorithm.

Effectively identifies prototypes that best represent target data.

Abstract

In this work, we develop an optimal transport (OT) based framework to select informative prototypical examples that best represent a given target dataset. Summarizing a given target dataset via representative examples is an important problem in several machine learning applications where human understanding of the learning models and underlying data distribution is essential for decision making. We model the prototype selection problem as learning a sparse (empirical) probability distribution having the minimum OT distance from the target distribution. The learned probability measure supported on the chosen prototypes directly corresponds to their importance in representing the target data. We show that our objective function enjoys a key property of submodularity and propose an efficient greedy method that is both computationally fast and possess deterministic approximation guarantees. Empirical results on several real world benchmarks illustrate the efficacy of our approach.