Book Image

D3.js Quick Start Guide

By : Matthew Huntington

Book Image

D3.js Quick Start Guide

By: Matthew Huntington

Overview of this book

D3.js is a JavaScript library that allows you to create graphs and data visualizations in the browser with HTML, SVG, and CSS. This book will take you from the basics of D3.js, so that you can create your own interactive visualizations, to creating the most common graphs that you will encounter as a developer, scientist, statistician, or data scientist. The book begins with an overview of SVG, the basis for creating two-dimensional graphics in the browser. Once the reader has a firm understanding of SVG, we will tackle the basics of how to use D3.js to connect data to our SVG elements. We will start with a scatter plot that maps run data to circles on a graph, and expand our scatter plot to make it interactive. You will see how you can easily allow the users of your graph to create, edit, and delete run data by simply dragging and clicking the graph. Next, we will explore creating a bar graph, using external data from a mock API. After that, we will explore animations and motion with a bar graph, and use various physics-based forces to create a force-directed graph. Finally, we will look at how to use GeoJSON data to create a map.

Preface

Who this book is for

What this book covers

To get the most out of this book

Free Chapter

Getting Started with D3.js

Getting Started with D3.js

What makes D3 so special?

This book's approach to learning

A preview of each build

Using SVG to Create Images Using Code

Using SVG to Create Images Using Code

Positioning an element

Styling an element

Important SVG elements

Building an Interactive Scatter Plot

Building an Interactive Scatter Plot

Adding a link to the D3 library

Adding an<svg>tag and sizing it with D3

Creating some fake data for our app

Adding SVG circles and styling them

Creating a linear scale

Attaching data to visual elements

Use data attached to a visual element to affect its appearance

Creating a time scale

Parsing and formatting times

Setting dynamic domains

Dynamically generating SVG elements

Displaying data in a table

Making a Basic Scatter Plot Interactive

Making a Basic Scatter Plot Interactive

Creating a click handler

Dragging an element

Updating data after a drag

Creating a zoom behavior that scales elements

Updating axes when zooming and panning

Updating click points after a transform

Avoiding redrawing the entire screen during rendering

Hiding elements beyond an axis

Creating a Bar Graph Using a Data File

Creating a Bar Graph Using a Data File

Setting up our application

Creating an external file to hold our data

Making an AJAX request

Using AJAX data to create SVG elements

Adjusting the height and the width of the bars

Adjusting the horizontal and the vertical placement of the bars

Making the width of the bars dynamic

Changing the color of the bar based on data

Animating SVG Elements to Create an Interactive Pie Chart

Animating SVG Elements to Create an Interactive Pie Chart

Setting up the application

Create data/configuration variables

Creating an ordinal scale

Creating the color scale to map labels to colors

Setting up the SVG

Adding paths for each pie segment

Generating an arc creating function

Formatting the data for the arc

Adjusting the position of the pie

Making a donut graph

Removing parts of the pie

Using Physics to Create a Force-Directed Graph

Using Physics to Create a Force-Directed Graph

What is a force-directed graph?

How to set up a graph of relationships

Setting up the HTML

Setting up styling for nodes and links

Setting up the SVG

Adding data for people

Adding data for relationships

Add circles to the SVG

Adding lines to the SVG

Creating a simulation

Specifying how the simulation affects visual elements

Creating forces

Mapping

Defining GeoJSON

Setting up the HTML

Using a projection

Generating a path using a projection and GeoJSON data

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Positioning an element

The <svg> tag is an inline element, such as an image (as opposed to a block element such as a <div>). Elements within the <svg> are positioned similar to Photoshop, with a set of coordinates that follow the form (x,y). An example of this could be (10,15), which translates to x=10 and y=15. This is different than HTML, where elements are laid out relative to one another. Here are some important things to keep in mind:

The point (0,0) is the upper–left corner of the <svg> element.
As y values increase, the point moves vertically down the <svg> element.
Don't confuse this with a typical coordinate system that has (0,0) at the lower–left corner with a point moving up, as y increases in value. This diagram shows the difference between a traditional coordinate system and an SVG coordinate system:

We can use...