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Contents at a Glance
About the Author xiii
About the Technical Reviewer xv
Acknowledgments xvii
■■Chapter 1: Background 1
■■Chapter 2: R Language Primer 25
■■Chapter 3: A Deeper Dive into R 47
■■Chapter 4: Data Visualization with D3 65
■■Chapter 5: Visualizing Spatial Data from Access Logs 85
■■Chapter 6: Visualizing Data Over Time 111
■■Chapter 7: Bar Charts 133
■■Chapter 8: Correlation Analysis with Scatter Plots 157
■■Chapter 9: Visualizing the Balance of Delivery and Quality with
Parallel Coordinates 177
Index 193
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Chapter 1
Background
There is a new concept emerging in the field of web development: using data visualizations munication tools.
This concept is something that is already well established in other fields and departments. At pany where
you work, your finance department probably uses data visualizations to represent fiscal information both internally
and externally; just take a look at the quarterly earnings reports for almost any publicly pany. They are
full of charts to show revenue by quarter, or year over year earnings, or a plethora of other historic financial data.
All are designed to show lots and lots of data points, potentially pages and pages of data points, in a single easily
digestible graphic.
Compare the bar chart in Google’s quarterly earnings report from back in 2007 (see Figure 1-1) to a subset of the
data it is based on in tabular format (see Figure 1-2).
Figure 1-1. Google Q4 2007 quarterly revenue shown in a bar chart
1
Chapter 1 ■ Background
Figure 1-2. Similar earnings data in tabular form
The bar chart is imminently more readable. We can clearly see by the shape of it that earnings are up and
have been steadily going up each quarter. By the color-coding, we can see the sources of