Graphics Reference
In-Depth Information
Looking at the chart, you can answer the previous question regarding
median income of Sales versus Construction. Near the bottom (at the 7
o'clock orientation), Sales is blue, while Construction on the left (at the 10
o'clock orientation) is purple, meaning that Construction has the higher
median income.
Note that the individual occupations are now slivers around the perimeter
and vary in size indicating the number of people employed in an occupation.
Some slivers are thin and difficult to discern. Interactive versions of
hierarchical pies allow the user to drill down and drill up by clicking wedges
(to drill down) or the center (to drill up). This enables the user to explore
large hierarchies.
Note
To see an example of this, visit
www.jasondavies.com/coffee-wheel/
.
Both treemaps and hierarchical pie charts are effective at showing two data
attributes via size and color. A
node-and-link graph
can display the
tree data and potentially use more visual attributes to convey additional
information.
Figure 10-9
shows the use of the same data as a graph.
Cytoscape provides a wide variety of visual attributes that can be used to
encode data, and here the node outline has been made wider and colored to
indicate change in income.
In the node-and-link graph view, the intermediate nodes are prominent,
just as they were in the hierarchical pie chart. The additional outline color
indicates the change in median income over the 10-year period from 2000
to 2010, a period when many jobs were moved offshore.
Outline color is dark gray between 0 percent and 30 percent change in
income. Because the threshold over the 10-year period was 30 percent, 30
percent is set as the Consumer Price Index (CPI), a widely used measure of
inflation. Effectively, a change in income under 30 percent does not keep up
with inflation.
