Graphics Reference
In-Depth Information
Whereas the person who is only familiar with entering the time and power
level on a microwave must either endure poor-tasting meals or stick only to
the handful of good ones, people who understand the ingredients and actu-
ally know how to cook have fewer limitations. The skilled chef might even
transform an average frozen dinner into a gourmet meal.
Likewise, with visualization, when you know how to interpret data and how
graphical elements fit and work together, the results often come out better
than software defaults.
VISUALIZATION COMPONENTS
Note: Cartographer Jacques Bertin described
a similar breakdown in Semiology of Graphics ,
and statistician Leland Wilkinson later provided
a variation in The Grammar of Graphics .
What are the ingredients of visualization? Figure 3-2 shows
a breakdown into four components, with data as the driving
force behind them: visual cues, coordinate system, scale, and
context. Each visualization, regardless of where it is on the spec-
trum, is built on data and these four components. Sometimes,
they are explicitly displayed, and other times they form an invisible framework.
The components work together, and your choice with one affects the others.
VISUAL CUES
In its most basic form, visualization is simply mapping data to geometry and
color. It works because your brain is wired to find patterns, and you can switch
back and forth between the visual and the numbers it represents. This is the
important bit. You must make sure that the essence of the data isn't lost in
that back and forth between visual and the value it represents because if you
can't map back to the data, the visualization is just a bunch of shapes.
You must choose the right visual cue, which changes by purpose, and you
must use it correctly, which depends on how you perceive the varied shapes,
sizes, and shades. Figure 3-3 shows what's available.
Position
When you use position as a visual cue, you compare values based on where
others are placed in a given space or coordinate system. For example, when
you look at a scatterplot, as shown in Figure 3-4, you judge a data point based
on its x- and y-coordinate and where it is relative to others.
FIGUREĀ 3-2 (following page)
TheĀ components of visualization
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