Deborah F. Swayne, Andreas Buja and Duncan Temple Lang
Exploratory Visual Analysis of Graphs in GGobi
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Graphs have long been of interest in telecommunications and social
network analysis, and they are now receiving increasing attention
from statisticians working in other areas, particularly in
biostatistics.  Most of the visualization software available for
working with graphs has come from outside statistics and has not
included the kind of interaction that statisticians have come to
expect.  At the same time, most of the exploratory visualization
software available to statisticians has made no provision for the
special structure of graphs.

Graphics software for the exploratory visual analysis of graph data
should include the following: graph layout methods; a variety of
displays and methods for exploring variables on both nodes and edges,
including methods that allow these covariate displays to be linked to
the network view; methods for thinning or otherwise trimming a large
graph.  In addition, the power of the visualization software is
greater if it can be smoothly linked to an extensible and interactive
statistics environment.

In this paper, we will describe how these goals have been addressed
in GGobi through its data format, architecture, graphical user
interface design, and its relationship to the R software
(Ihaka and Gentleman, 1996).