Group-in-a-Box Meta-Layouts for Topological Clusters and Attribute-Based Groups: Space-Efficient Visualizations of Network Communities and Their Ties

An important part of network analysis is understanding community structures like topological clusters and attribute-based groups. Standard approaches for showing communities using colour, shape, rectangular bounding boxes, convex hulls or force-directed layout algorithms remain valuable, however our Group-in-a-Box meta-layouts add a fresh strategy for presenting community membership, internal structure and inter-cluster relationships. This paper extends the basic Group-in-a-Box meta-layout, which uses a Treemap substrate of rectangular regions whose size is proportional to community size. When there are numerous inter-community relationships, the proposed extensions help users view them more clearly: (1) the Croissant-Doughnut meta-layout applies empirically determined rules for box arrangement to improve space utilization while still showing inter-community relationships, and (2) the Force-Directed layout arranges community boxes based on their aggregate ties at the cost of additional space. Our free and open source reference implementation in NodeXL includes heuristics to choose what we have found to be the preferable Group-in-a-Box meta-layout to show networks with varying numbers or sizes of communities. Case study examples, a pilot comparative user preference study (nine participants), and a readability measure-based evaluation of 309 Twitter networks demonstrate the utility of the proposed meta-layouts.