Graphics Reference
In-Depth Information
Figure 13-3:
Mapping size to value of shipments and using a modularity
analytic identifies regions of flow and a few broad patterns. However,
overlapping nodes make it difficult to see links.
Notice that the modularity clusters (which are computed based solely on
the topology of flow between nodes) map nicely into geospatial regions.
In fact, not only do the clusters have pure spatial boundaries, they are
almost exactly the same as the four official national regions defined by
the United States Census Bureau. Given that census regions are defined
primarily for statistical purposes, it seems very likely that the states within
have additional statistical attributes that unite them outside of this data set.
Thoughthemodularityanalytictellsyoutherearemorecyclesofflowwithin
the four state groups, it is difficult to see it. It's particularly difficult to
see much of anything in areas like the Northeast, where there is a lot of
overlap. This is where Beck's lesson comes into play. To see relationships
more clearly, a schematic geographic layout would be ideal.
Use the Label Adjust layout to shift the nodes for legibility. Return to the
Preview task mode, turn off the curve option on links, and give edge arrows
a relative size of 2.0.
By separating nodes, the links between them have become visible, revealing
characteristics that were previously obscured, as shown in
Figure 13-4
.
For
