Accelerated D2-Clustering Algorithm for Large-Scale Data
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Solution Overview
Problem
The D2-clustering algorithm for discrete distributions under the Wasserstein distance faces significant computational complexity issues, making it impractical for large-scale data sets, particularly in applications like image and video annotation, where the number of training images can reach millions, due to its polynomial time complexity.
Innovation Solution
The development of the Accelerated D2-clustering (AD2-clustering) algorithm, which employs subgradient descent, alternating direction method of multipliers (ADMM), and a modified Bregman ADMM, along with a parallel computing approach using a hierarchical structure, to optimize the Wasserstein centroids and reduce computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If D2-clustering algorithm is used for discrete distributions under Wasserstein distance, then clustering quality is improved, but computational complexity increases polynomially making it impractical for large-scale data sets
Solution Approach 1:
The patent segments the large-scale clustering problem into multiple smaller sub-problems by dividing the data set into batches. Each batch is processed independently to compute local centroids, which are then aggregated to form global centroids. This segmentation reduces the polynomial computational complexity of processing the entire data set at once, enabling scalable clustering while maintaining Wasserstein distance-based quality metrics.
Solution Approach 2:
The patent performs preliminary actions by pre-computing and storing distance matrices between data points and potential centroids before the main clustering iteration. This pre-computation step caches reusable distance information, avoiding redundant calculations during subsequent clustering iterations and significantly reducing the overall computational burden for large data sets.
2Measurement precision
If linear programming is used to solve Wasserstein distance in D2-clustering, then accurate distance measurement is achieved, but computational time increases polynomially with sample size
Solution Approach 1:
The patent performs preliminary computation of distance matrices between all pairs of points in the discrete distributions before solving the linear programming problem. These pre-computed distances are stored and reused during the centroid update iterations, eliminating the need to recompute them repeatedly and significantly reducing the total computational time while preserving accurate Wasserstein distance measurements.
Solution Approach 2:
The patent dynamically updates only the necessary portions of distance information during clustering iterations rather than recomputing entire distance matrices. By tracking which distance values need updating based on current centroid positions and data assignments, the method adapts the computational effort to the actual state of the clustering process, reducing redundant calculations.
Data Source
AI summary
Computationally efficient accelerated D2-clustering algorithms are disclosed for clustering discrete distributions under the Wasserstein distance with improved scalability. Three first-order methods include subgradient descent method with re-parametrization, alternating direction method of multipliers (ADMM), and a modified version of Bregman ADMM. The effects of the hyper-parameters on robustness, convergence, and speed of optimization are thoroughly examined. A parallel algorithm for the modified Bregman ADMM method is tested in a multi-core environment with adequate scaling efficiency subject to hundreds of CPUs, demonstrating the effectiveness of AD2-clustering.


