Interactive Visualization of Hierarchically Structured Data

ABSTRACT

We introduce methods for visualization of data structured along trees, especially hierarchically structured collections of time series. To this end, we identify questions that often emerge when working with hierarchical data and provide an R package to simplify their investigation. Our key contribution is the adaptation of the visualization principles of focus-plus-context and linking to the study of tree-structured data. Our motivating application is to the analysis of bacterial time series, where an evolutionary tree relating bacteria is available a priori. However, we have identified common problem types where, if a tree is not directly available, it can be constructed from data and then studied using our techniques. We perform detailed case studies to describe the alternative use cases, interpretations, and utility of the proposed visualization methods.

KEYWORDS:

• D3
• Focus-plus-context
• Linking
• R
• Time-series
• Tree-structured

Funding

This research was supported in part by an NIH training grant (5T32GM096982-03) and a Weiland Fellowship. It was also supported in part by NIH grant R01 AI112401.

Notes

1 We use the colorbrewer palette to facilitate readability (Brewer et al. 2003).

2 However, the code for this approach is available publicly, in a separate branch of treelapse: https://github.com/krisrs1128/treelapse/tree/combined-brushes.