Getting Started with D3.js

The era of big data is upon us! Advances in hardware have made it possible for computers to store, analyze, and transmit massive amounts of information in a way that was previously impossible. Data science has become one of the most in-demand fields in the United States, and companies are constantly coming up with new techniques to analyze customer information; it seems as if every day there are new ways to visualize all this data. D3 has become the most popular library used to create dynamic, interactive, data-driven visualizations on the web. Unlike many technologies previously used in data vizualization
, D3 leverages the power of combining SVG images with web browsers and JavaScript. In this chapter, we'll discuss the following topics:

What is SVG?
What makes D3 so special?
This book's approach to learning

What is SVG?

One of the best ways to present your data is via an interactive graphic on the web. The advantage of this approach is that its interactivity allows creators to pack more information into a single visualization, while the ubiquity of the web allows anyone to instantly access it. Gone are the days of PowerPoint presentations, or, worse still, printing static images on to paper as handouts. There are many ways to create a web-based interactive data visualization, but none of them is more popular than the JavaScript library called D3.js.

To understand why D3.js works so well, it's important to understand what SVG is and how it relates to D3. SVG stands for Scalable Vector Graphics, and it's a way to display shapes using mathematical directions/commands. Traditionally, the information for an image is stored in a grid, also called a raster. Each square (called a pixel) of the image has a specific color:

But with SVG, a set of succinct drawing directions is stored. For example, the drawing command for a circle is as follows:

<circle r=50><circle>

This code produces a much smaller file size, and because it's a set of drawing directions, the image can be enlarged without any pixelation. A raster image becomes blurry and pixelated as it's enlarged. The advantage of raster graphics over vector graphics is that they're great for storing complex images such as photographs. With a photograph, where each pixel probably has a different color, it's better to use a raster image. Imagine writing SVG drawing commands for a photograph: you would end up creating a new element for each pixel, and the file size would be too large.

Once an SVG drawing command is written, a program needs to interpret the command and display the image. Up until recently, only designated drawing applications such as Adobe Illustrator could view and manipulate these images. But by 2011 all major modern browsers supported SVG tags, allowing for developers to embed SVG directly on a web page. Since the SVG image was directly embedded in the code of a web page, JavaScript, which normally is used for manipulating HTML, could be used to manipulate the shape, size, and colors of the image in response to user events. To make the circle in the SVG example you have just seen grow to twice its original size, all that JavaScript had to do was change the rattribute:

<circle r=100><circle>

This was the massive breakthrough that allowed complex interactive data visualizations to be hosted on the web.

A preview of each build

Each chapter focuses on a specific build. The completed build code for each chapter can be found at: https://github.com/PacktPublishing/D3.js-Quick-Start-Guide.

Using SVG to create images using code

In this chapter, we learn how to render shapes in the browser, using SVG. We'll cover shapes such as these:

Circles:

Lines:

Rectangles:

Ellipses:

Polygons:

Polylines:

Cubic Bezier Curves:

The completed code for this section can be found here: https://github.com/PacktPublishing/D3.js-Quick-Start-Guide/tree/master/Chapter02.

Building an interactive scatter plot

In this chapter, you'll learn how to plot points on a graph to create a scatter plot. It will look a bit like this:

The completed code for this section can be found here: https://github.com/PacktPublishing/D3.js-Quick-Start-Guide/tree/master/Chapter03.

Making a basic scatter plot interactive

This chapter builds on the previous one, adding interactive functionality that allows you to do the following:

Create new points:

Remove points:

Update points:

Zoom and pan:

The completed code for this section can be found here: https://github.com/PacktPublishing/D3.js-Quick-Start-Guide/tree/master/Chapter04.

Creating a bar graph using a data file

In this chapter, we'll learn how to use AJAX to make an asynchronous call, after the page has loaded, to retrieve some JSON data and render it as a bar graph. It should look as follows:

The completed code for this section can be found here: https://github.com/PacktPublishing/D3.js-Quick-Start-Guide/tree/master/Chapter05.

Animating SVG elements to create an interactive pie chart

In this chapter, we'll learn how to make a pie chart:

Then we'll turn it into a donut chart:

And then we'll create functionality so that the user can remove a section of the chart and it will close the gap with a smooth transition:

The completed code for this section can be found here: https://github.com/PacktPublishing/D3.js-Quick-Start-Guide/tree/master/Chapter06.

Using physics to create a force-directed graph

In this chapter, we'll graph relationships between people with a force-directed graph. It will look as follows:

The completed code for this section can be found here: https://github.com/PacktPublishing/D3.js-Quick-Start-Guide/tree/master/Chapter07.

Mapping

In Chapter 8, Mapping, we'll learn how to use GeoJSON data to create a map of the world. It will look as follows:

The completed code for this section can be found here: https://github.com/PacktPublishing/D3.js-Quick-Start-Guide/tree/master/Chapter08.

L. Dec 21, 2018

It isn't always easy to know what book to start with for software. I was a bit worried about getting a D3 book that would be too advanced, or worse, not have enough information. This was perfect. The explanations are easy to understand and the code is presented in a logical order so users learn "why" as they go. Highly recommended for those who are D3 beginners but need something that goes as far as dynamic graphing of external data. This is not a huge book because it doesn't need to be to get the point across. Well done and timely.

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D3.js Quick Start Guide: Create amazing, interactive visualizations in the browser with JavaScript

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D3.js Quick Start Guide

Getting Started with D3.js

What is SVG?

What makes D3 so special?

This book's approach to learning

A preview of each build

Using SVG to create images using code

Building an interactive scatter plot

Making a basic scatter plot interactive

Creating a bar graph using a data file

Animating SVG elements to create an interactive pie chart

Using physics to create a force-directed graph

Mapping

Setting up

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Key benefits

Description

Who is this book for?

What you will learn

Product Details

What do you get with Print?

Contact Details

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Product Details

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Frequently bought together

Table of Contents

Recommendations for you

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