HCMapper: An interactive visualization tool to compare partition-based flat clustering extracted from pairs of dendrograms

TL;DR

HCMapper is an interactive visualization tool designed to compare pairs of dendrograms from hierarchical clustering, enabling quick assessment of hypothesis agreement and data point discrepancies across multiple scales.

Contribution

It introduces a novel visualization method for comparing hierarchical clustering results, focusing on multiscale partition structures and hypothesis testing.

Findings

Facilitates rapid visual comparison of dendrograms

Helps identify data points with conflicting cluster assignments

Supports multiscale analysis of hierarchical clustering results

Abstract

We describe a new visualization tool, dubbed HCMapper, that visually helps to compare a pair of dendrograms computed on the same dataset by displaying multiscale partition-based layered structures. The dendrograms are obtained by hierarchical clustering techniques whose output reflects some hypothesis on the data and HCMapper is specifically designed to grasp at first glance both whether the two compared hypotheses broadly agree and the data points on which they do not concur. Leveraging juxtaposition and explicit encodings, HCMapper focus on two selected partitions while displaying coarser ones in context areas for understanding multiscale structure and eventually switching the selected partitions. HCMapper utility is shown through the example of testing whether the prices of credit default swap financial time series only undergo correlation. This use case is detailed in the supplementary material as well as experiments with code on toy-datasets for reproducible research. HCMapper is currently released as a visualization tool on the DataGrapple time series and clustering analysis platorm at www.datagrapple.com.