Fry - Visualizing Data

Copyright 2008 Ben Fry

When I show visualization projects to an audience, one of the most common questions is, "How do you do this?" Other books about data visualization do exist, but the most prominent ones are often collections of academic papers; in any case, few explain how to actually build representations. Books from the field of design that offer advice for creating visualizations see the field only in terms of static displays, ignoring the possibility of dynamic, software-based visualizations. A number spend most of their time dissecting what's wrong with given representationssometimes providing solutions, but more often not.

In this book, I wanted to offer something for people who want to get started building their own visualizations, something to use as a jumping-off point for more complicated work. I don't cover everything, but I've tried to provide enough background so that you'll know where to go next.

I wrote this book because I wanted to have a way to make the ideas from Computational Information Design , my Ph.D. dissertation, more accessible to a wider audience. More specifically, I wanted to see these ideas actually applied, rather than limited to an academic document on a shelf. My dissertation covered the process of getting from data to understanding; in other words, from considering a pile of information to presenting it usefully, in a way that can be easily understood and interacted with. This process is covered in , and used throughout the book as a framework for working through visualizations.

Most of the examples in this book are written from scratch. Rather than relying on toolkits or libraries that produce charts or graphs, instead you learn how to create them using a little math, some lines and rectangles, and bits of text. Many readers may have tried some toolkits and found them lacking, particularly because they want to customize the display of their information. A tool that has generic uses will produce only generic displays, which can be disappointing if the displays do not suit your data set. Data can take many interesting forms that require unique types of display and interaction; this book aims to open up your imagination in ways that collections of bar and pie charts cannot.

This book uses Processing (http://processing.org), a simple programming environment and API that I co-developed with Casey Reas of UCLA. Processing's programming environment makes it easy to sit down and "sketch" code to produce visual images quickly. Once you outgrow the environment, it's possible to use a regular Java IDE to write Processing code because the API is based on Java. Processing is free to download and open source. It has been in development since 2001, and we've had about 100,000 people try it out in the last 12 months. Today Processing is used by tens of thousands of people for all manners of work. When I began writing this book, I debated which language and API to use. It could have been based on Java, but I realized I would have found myself re-implementing the Processing API to make things simple. It could have been based on Actionscript and Flash, but Flash is expensive to buy and tends to break down when dealing with larger data sets. Other scripting languages such as Python and Ruby are useful, but their execution speeds don't keep up with Java. In the end, Processing was the right combination of cost, ease of use, and execution speed.