Data Visualization with D3.js Cookbook

Table of Contents

Data Visualization with D3.js Cookbook

Credits

About the Author

About the Reviewers

www.PacktPub.com

Support files, eBooks, discount offers and more

Why Subscribe?

Free Access for Packt account holders

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Getting Started with D3.js

Introduction

Setting up a simple D3 development environment

Getting Ready

How to do it...

How it works...

There's more...

How to get source code

Setting up an NPM-based development environment

Getting Ready

How to do it...

How it works...

There's more...

Setup a local HTTP server

Python Simple HTTP Server

Node.js HTTP Server

Understanding D3-style JavaScript

Getting ready

How to do it...

How it works...

Functions are objects

Static variable scoping

Variable-parameter function

Function chaining

There's more...

Finding and sharing code

How to get help

2. Be Selective

Introduction

Selecting a single element

Getting ready

How to do it...

How it works...

Selecting multiple elements

Getting ready

How to do it...

How it works...

Iterating through a selection

Getting ready

How to do it...

How it works...

Performing subselection

Getting ready

How to do it...

How it works...

Function chaining

Getting ready

How to do it...

How it works...

Manipulating the raw selection

Getting ready

How to do it...

How it works...

3. Dealing with Data

Introduction

The enter-update-exit pattern

Binding an array as data

Getting Ready

How to do it...

How it works...

Binding object literals as data

Getting Ready

How to do it...

How it works...

Binding functions as data

Getting Ready

How to do it...

How it works...

Working with arrays

Getting Ready

How to do it...

How it works...

Filtering with data

Getting Ready

How to do it...

How it works...

Sorting with data

Getting Ready

How to do it...

How it works...

Loading data from a server

Getting Ready

How to do it...

How it works...

4. Tipping the Scales

Introduction

What are scales?

Using quantitative scales

Getting Ready

How to do it...

How it works...

There's more...

Using the time scale

Getting Ready

How to do it...

How it works...

There's more...

See also

Using the ordinal scale

Getting Ready

How to do it...

How it works...

Interpolating a string

Interpolator

Getting Ready

How to do it...

How it works...

There's more...

Interpolating colors

Getting Ready

How to do it...

How it works...

See also

Interpolating compound objects

Getting Ready

How to do it...

How it works...

Implementing a custom interpolator

Getting Ready

How to do it...

How it works...

See also

5. Playing with Axes

Introduction

Working with basic axes

Getting Ready

How to do it...

How it works...

Customizing ticks

Getting Ready

How to do it...

How it works...

Drawing grid lines

Getting Ready

How to do it...

How it works...

Dynamic rescaling of axes

Getting Ready

How to do it...

How it works...

6. Transition with Style

Introduction

What is Transition?

Animating a single element

Getting Ready

How to do it...

How it works...

Animating multiple elements

Getting Ready

How to do it...

How it works...

Using ease

Getting Ready

How to do it...

How it works...

Using tweening

Getting Ready

How to do it...

How it works...

There's more...

Using transition chaining

Getting Ready

How to do it...

How it works...

Using transition filter

Getting Ready

How to do it...

How it works...

See also

Listening to transitional events

Getting Ready

How to do it...

How it works...

Implementing a custom interpolator

Getting Ready

How to do it...

How it works...

Working with timer

Getting Ready

How to do it...

How it works...

See also

7. Getting into Shape

Introduction

What is SVG?

Vector

Scalability

Creating simple shapes

Getting Ready

How to do it...

How it works...

There's more...

D3 SVG shape generators

See also

Using a line generator

Getting Ready

How to do it...

How it works...

See also

Using line interpolation

Getting Ready

How to do it...

How it works...

Changing line tension

Getting Ready

How to do it...

How it works...

Using an area generator

Getting Ready

How to do it...

How it works...

Using area interpolation

Getting Ready

How to do it...

How it works...

There's more...

See also

Using an arc generator

Getting Ready

How to do it...

How it works...

Implementing arc transition

Getting Ready

How to do it...

How it works...

There's more...

See also

8. Chart Them Up

Introduction

Creating a line chart

Getting ready

How to do it...

How it works...

Creating an area chart

Getting ready

How to do it...

How it works...

Creating a scatter plot chart

Getting ready

How to do it...

How it works...

Creating a bubble chart

Getting ready

How to do it...

How it works...

Creating a bar chart

Getting ready

How to do it...

How it works...

See also

9. Lay Them Out

Introduction

Building a pie chart

Getting ready

How to do it...

How it works...

There's more...

See also

Building a stacked area chart

Getting ready

How to do it...

How it works...

There's more...

Expanded area chart

Streamgraph

See also

Building a treemap

Getting ready

How to do it...

How it works...

See also

Building a tree

Getting ready

How to do it...

How it works...

See also

Building an enclosure diagram

Getting ready

How to do it...

How it works...

See also

10. Interacting with your Visualization

Introduction

Interacting with mouse events

Getting ready

How to do it...

How it works...

There's more...

See also

Interacting with a multi-touch device

Getting ready

How to do it...

How it works...

There's more...

See also

Implementing zoom and pan behavior

Getting ready

How to do it...

How it works...

There's more...

See also

Implementing drag behavior

Getting ready

How to do it...

How it works...

There's more...

See also

11. Using Force

Introduction

Using gravity and charge

Getting ready

How to do it...

How it works...

Charge

Gravity

Friction

Setting up zero force layout

Setting up mutual repulsion

Setting up mutual attraction

Setting up gravity

Using gravity with repulsion

See also

Generating momentum

Getting ready

How to do it...

How it works...

See also

Setting the link constraint

Getting ready

How to do it...

How it works...

See also

Using force to assist visualization

Getting ready

How to do it...

How it works...

See also

Manipulating force

Getting ready

How to do it...

How it works...

See also

Building a force-directed graph

Getting ready

How to do it...

How it works...

See also

12. Know your Map

Introduction

Projecting the US map

GeoJSON

TopoJSON

Getting ready

How to do it...

How it works...

See also

Projecting the world map

Getting ready

How to do it...

How it works...

See also

Building a choropleth map

Getting ready

How to do it...

How it works...

See also

13. Test Drive your Visualization

Introduction

Introduction to unit testing

Getting Jasmine and setting up the test environment

Getting ready

How to do it...

How it works...

See also

Test driving your visualization – chart creation

How to do it...

How it works...

Test driving your visualization – SVG rendering

How to do it...

How it works...

Test driving your visualization – pixel-perfect bar rendering

How to do it...

How it works...

See also

A. Building Interactive Analytics in Minutes

Introduction

The crossfilter.js library

How to do it...

How it works...

There's more...

See also

Dimensional charting – dc.js

Getting ready

How to do it...

How it works...

There's more...

See also

Index

Data Visualization with D3.js Cookbook

Data Visualization with D3.js Cookbook

Copyright © 2013 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.

Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

First published: October 2013

Production Reference: 1171013

Published by Packt Publishing Ltd.

Livery Place

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Birmingham B3 2PB, UK.

ISBN 978-1-78216-216-2

www.packtpub.com

Cover Image by Martin Bell (<[email protected]>)

Credits

Author

Nick Qi Zhu

Reviewers

Andrew Berls

Kevin Coughlin

Ismini Lourentzou

Pablo Navarro

Acquisition Editor

Martin Bell

Lead Technical Editor

Sweny M. Sukumaran

Technical Editors

Akashdeep Kundu

Proshonjit Mitra

Sonali S. Vernekar

Project Coordinator

Kranti Berde

Proofreader

Mario Cecere

Indexer

Tejal Soni

Graphics

Yuvraj Mannari

Production Coordinator

Aditi Gajjar

Cover Work

Aditi Gajjar

About the Author

Nick Qi Zhu is a professional programmer and visualization enthusiast with more than a decade of experience in software development. He is the author of dc.js—a popular multi-dimensional charting library built on D3. Currently he is having fun and learning as a lead consultant at ThoughtWorks.

I would like to thank the folks at Packt Publishing for supporting me through my journey, especially my editors Martin Bell and Sweny Sukumaran for polishing up my prose making this book much easier to read. And many thanks to my technical reviewers who had really made this book a much better one through their constructive criticism.

Finally to my wife Sherry for being supportive and incredibly patient with me through the last several months; without her support this book would not be possible.

About the Reviewers

Andrew Berls is a Ruby and JavaScript developer and lives in Santa Barbara, CA. He's been building websites ever since he learned what an HTML tag was, and has since fallen in love with full-stack application development. He was recently an intern at Causes.com, where he developed data dashboards using D3.js for visualizing social networks. Andrew is completing his degree in Computer Science at the University of California, Santa Barbara, and when he's not programming you can find him learning to cook (badly) or hiking up a mountain somewhere.

Kevin Coughlin holds both Computer Science and Economics degrees from The College of New Jersey. He is a JavaScript developer with over two years of industry experience. At work and at home, Kevin combines HTML5 standards with cutting-edge client- and server-side technologies such as Angular.js, Backbone.js, and Node.js to produce effective modern solutions for the open web.

Kevin regularly posts tutorials on emerging web technologies on his website http://kevintcoughlin.com.

Ismini Lourentzou has a Business Administration B.Sc. and a long-standing career in the banking sector, at National Bank of Greece. Learning programming in Java in her spare time and her continuous urge for novelty, drove her to pursue a second degree in Computer Science from Athens University of Economics and Business (AUEB). During her undergraduate studies, she has participated in the Knowledge Discovery and Data Mining Cup 2012, as a member of the Data and Web Mining Group of AUEB, headed by Professor Michalis Vazirgiannis, and worked on Automated Snippet Generation of Online Advertising, which led to a publication at CIKM 2013. Meanwhile, she also participated at ImageClef 2013 as a member of the Information Retrieval Group of AUEB, headed by Professor Theodore Kalamboukis. Their participation was placed second in the Textual Ad-hoc image-based retrieval and fifth in Visual Ad-hoc image-based retrieval. Due to her love for research and programming, there was no doubt about changing her career orientation; she is currently a PhD student at University of Illinois at Urbana – Champaign, combining Machine Learning and Information Retrieval in developing intelligent information systems that will improve a user's productivity by decreasing the amount of manual involvement in searching, organizing, and understanding information from mainly textual sources. After completing her PhD, she hopes to continue working in research, and to be able to learn more and more each day.

I would like to thank my family for their support and help, for always being there to motivate me, my mother for taking care of me while my free time was nonexistent, my sister that is always protective of me, my father to being present during difficult situations. Moreover, I am thankful for my boyfriend for his everlasting patience and love and my friends for their advices and help during this process.

Pablo Navarro is a data visualization consultant from Chile. He earned his Master's degree in Applied Mathematics from École des Mines de Saint-Etienne, France. After working for some years in operations research and data analysis, he decided to specialize in data visualization for web platforms, in which he currently works. In his free time, he enjoys doing watercolor illustrations, running and reading about human evolution. His most recent works can be seen at http://pnavarrc.github.io.

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Preface

D3.js is a JavaScript library designed to display digital data in a dynamic graphical form. It helps you to bring data to life using HTML, SVG, and CSS. D3 allows great control over the final visual result, and it is the hottest and most powerful web-based data visualization technology on the market today.

This book is packed with practical recipes to help you learn every aspect of data visualization with D3. It is designed to provide you with all the guidance you need to get to grips with data visualization with D3. With this book, you will create breathtaking data visualization with professional efficiency and precision with the help of practical recipes, illustrations, and code samples.

This cookbook starts off by touching upon data visualization and D3 basics before gradually taking you through a number of practical recipes covering a wide range of topics you need to know about D3.

You will learn the fundamental concepts of data visualization, functional JavaScript, and D3 fundamentals including element selection, data binding, animation, and SVG generation. You will also learn how to leverage more advanced techniques such as custom interpolators, custom tweening, timers, the layout manager, force manipulation, and so on. This book also provides a number of prebuilt chart recipes with ready-to-go sample code to help you bootstrap quickly.

What this book covers

Chapter 1, Getting Started with D3.js, is designed to get you up and running with D3.js. It covers the fundamental aspects such as what D3.js is and how to set up a typical D3.js data visualization environment.

Chapter 2, Be Selective, teaches you one of the most fundamental tasks you need to perform with any data visualization project using D3—selection. Selection helps you target certain visual elements on the page.

Chapter 3, Dealing with Data, explores the most essential question in any data visualization project—how data can be represented both in programming constructs, and its visual metaphor.

Chapter 4, Tipping the Scales, deals with a very important subdomain of data visualization. As a data visualization developer, one key task that you need to perform over and over again is to map values in your data domain to visual domain, which is the focus of this chapter.

Chapter 5, Playing with Axes, explores the usage of axes' component and some related techniques commonly used in Cartesian coordinate system based visualization.

Chapter 6, Transition with Style, deals with transitions. A picture is worth a thousand words, this age-old wisdom is arguably one of the most important cornerstones of data visualization. This chapter covers transition and animation support provided by D3 library.

Chapter 7, Getting into Shape, deals with Scalable Vector Graphics (SVG), which is a mature World Wide Web Consortium (W3C) standard widely used in visualization projects.

Chapter 8, Chart Them Up, explores one of the oldest and well trusted companions in data visualization—charts. Charts are well defined and well understood graphical representations of data.

Chapter 9, Lay Them Out, focuses on D3 Layout. D3 layouts are algorithms that calculate and generate placement information for a group of elements capable of generating some of the most complex and interesting visualization.

Chapter 10, Interacting with your Visualization, focuses on D3 human visualization interaction support, or in other words how to add computational steering capability to your visualization.

Chapter 11, Using Force, covers one of the most fascinating aspects of D3—Force. Force simulation is one of the most awe-inspiring techniques that you can add to your visualization.

Chapter 12, Know your Map, introduces basic D3 cartographic visualization techniques and how to implement a fully functional geographic visualization in D3.

Chapter 13, Test Drive your Visualization, teaches you to implement your visualization like a pro with Test Driven Development (TDD).

Appendix A, Building Interactive Analytics in Minutes serves as an introduction to Crossfilter.js and dc.js on interactive dimensional charting.

What you need for this book

A text editor: To edit and create HTML, CSS, and JavaScript files

A web browser: A modern web browser (Firefox 3, IE 9, Chrome, Safari 3.2 and above)

A local HTTP server: You need a local HTTP server to host data file for some of the more advanced recipes in this book. We will cover how to set up a Node or Python based simple HTTP server in the first chapter.

Git client (Optional): If you would like to check out the recipe source code directly from our Git repository, you need a Git client installed on your computer.

Who this book is for

If you are a developer or an analyst familiar with HTML, CSS, and JavaScript, and you wish to get the most out of D3, then this book is for you. This book can also serve as a desktop quick-reference guide for experienced data visualization developers.

Conventions

In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text are shown as follows: We can select HTML elements through the use of the d3.select function.

A block of code is set as follows:

instance.description = function (d) {

    if (!arguments.length) d;

    description = d;

    return instance;

};

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

instance.description = function (d) {

if (!arguments.length) d;

    description = d;

    return instance;

};

Any command-line input or output is written as follows:

> npm install http-server –g

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: clicking the Next button moves you to the next screen.

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.

Reader feedback

Feedback from our readers is always welcome. Let us know what you think about this book—what you liked or may have disliked. Reader feedback is important for us to develop titles that you really get the most out of.

To send us general feedback, simply send an e-mail to <[email protected]>, and mention the book title via the subject of your message.

If there is a topic that you have expertise in and you are interested in either writing or contributing to a book, see our author guide on www.packtpub.com/authors.

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Downloading the example code

You can download the example code files for all Packt books you have purchased from your account at http://www.packtpub.com. If you purchased this book elsewhere, you can visit http://www.packtpub.com/support and register to have the files e-mailed directly to you.

Errata

Although we have taken every care to ensure the accuracy of our content, mistakes do happen. If you find a mistake in one of our books—maybe a mistake in the text or the code—we would be grateful if you would report this to us. By doing so, you can save other readers from frustration and help us improve subsequent versions of this book. If you find any errata, please report them by visiting http://www.packtpub.com/submit-errata, selecting your book, clicking on the errata submission form link, and entering the details of your errata. Once your errata are verified, your submission will be accepted and the errata will be uploaded on our website, or added to any list of existing errata, under the Errata section of that title. Any existing errata can be viewed by selecting your title from http://www.packtpub.com/support.

Piracy

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We appreciate your help in protecting our authors, and our ability to bring you valuable content.

Questions

You can contact us at <[email protected]> if you are having a problem with any aspect of the book, and we will do our best to address it.

Chapter 1. Getting Started with D3.js

In this chapter we will cover:

Setting up a simple D3 development environment

Setting up an NPM-based development environment

Understanding D3-style JavaScript

Introduction

This chapter is designed to get you up and running with D3.js, covering fundamental aspects, such as what D3.js is, and how to set up a typical D3.js data visualization environment. One particular section is also devoted in covering some lesser known areas of JavaScript that D3.js relies heavily on.

What is D3? D3 refers to Data-Driven Documents, and according to the official D3 Wiki:

D3.js is a JavaScript library for manipulating documents based on data. D3 helps you bring data to life using HTML, SVG, and CSS. D3's emphasis on web standards gives you the full capabilities of modern browsers without tying yourself to a proprietary framework, combining powerful visualization components and a data-driven approach to DOM manipulation.

D3 Wiki (2013, August)

In a sense, D3 is a specialized JavaScript library that allows you to create amazing data visualizations using a simpler (data driven) approach by leveraging existing web standards. D3.js was created by Mike Bostock (http://bost.ocks.org/mike/) and superseded his previous work on a different JavaScript data visualization library called Protovis. For more information on how D3 was created and on the theory that influenced both Protovis and D3.js, please check out links in the following information box. Here in this book we will focus more on how to use D3.js to power your visualization. Initially, some aspects of D3 may be a bit confusing due to its different approach to data visualization using JavaScript. I hope that over the course of this book, a large number of topics, both basic and advanced, will make you comfortable and effective with D3. Once properly understood, D3 can improve your productivity and expressiveness with data visualizations by orders of magnitude.

Note

For more formal introduction to the idea behind D3 see the Declarative Language Design for Interactive Visualization paper published by Mike Bostock on IEEE InfoVis 2010 http://vis.stanford.edu/papers/protovis-design.