Graphics Reference
In-Depth Information
Figure 12-1:
One of the most highly regarded visualizations of all time is
Minard's depiction of Napoleon's ill-fated march on Russia in 1812. The use
of route width to indicate volume (here, the size of army as it is decimated)
can be applied with equal success to graph visualization.
This chapter describes how you can use graph visualization to reveal
structures and patterns of flow between and through nodes using various
techniques such as Sankey diagrams, traditional graph layouts with link
weight, chord diagrams, and behavioral factor trees. Web-based examples
and model code are provided for illustration.
Sankey Diagrams
Sankey diagrams
are an effective way to see volume of flow through
a multi-step process or system. In a Sankey diagram, the flows are
conventionally laid out left to right, and the width of a link indicates the
volume of flow. Incoming links always enter a node on the same side at right
angles, and outgoing links exit in the same way on the opposite side. At each
sideofthenode,linksarestackedattheirpointofentryandexittorepresent
the total incoming and outgoing volume.
Transactional data is often ideally visualized in Sankey form. For example,
money flow through various accounts can be represented in this way,
showing sources of funding and where the money is going. For a financial
crimes investigator, “following the money” is central to the task of
identifying theperpetrators offraud. Similarly, foran economist orbusiness
