Graph Compare: Simultaneous Graph Layout and Visualization for Structural Comparison

Graphs, node-link diagrams, are frequently used to visualize structured information. But while much work has gone into methods for visualizing single graphs, it is still an open question how to visualize multiple graphs to best convey their structural and semantic similarities and differences. We present a visualization technique for comparing graphs. At its core, our method is a graph layout algorithm that computes the layout for two graphs simultaneously so that they are easy to compare when placed side by side. In particular, our algorithm favors layouts where shared graph structure appears the same way in both graph layouts. We demonstrate how our method can work for graphs with and without unique vertex labels, using inexact graph matching techniques. We show visualizations produced by our algorithm and evaluate them in an informal user study, uncovering important design principles for visualizations that compare graphs.