Book Image

Learning D3.js 5 Mapping - Second Edition

By : Thomas Newton, Oscar Villarreal, Lars Verspohl
Book Image

Learning D3.js 5 Mapping - Second Edition

By: Thomas Newton, Oscar Villarreal, Lars Verspohl

Overview of this book

D3.js is a visualization library used for the creation and control of dynamic and interactive graphical forms. It is a library used to manipulate HTML and SVG documents as well as the Canvas element based on data. Using D3.js, developers can create interactive maps for the web, that look and feel beautiful. This book will show you how build and design maps with D3.js and gives you great insight into projections, colors, and the most appropriate types of map. The book begins by helping you set up all the tools necessary to build visualizations and maps. Then it covers obtaining geographic data, modifying it to your specific needs, visualizing it with augmented data using D3.js. It will further show you how to draw and map with the Canvas API and how to publish your visualization. By the end of this book, you'll be creating maps like the election maps and the kind of infographics you'll find on sites like the New York Times.
Table of Contents (13 chapters)
6
Finding and Working with Geographic Data

Foundation - creating your basic map

In this section, we will walk through the basics of creating a standard map.
The example can be viewed by opening the example-1.html file of this chapter provided with this book. If you already have the HTTP server running, you can point your browser to http://localhost:8080/chapter-4/example-1.html. On the screen is Mexico (Oscar's beloved country)!

Let's walk through the code to get a step-by-step explanation of how to create this map.

The width and height can be anything you want. Depending on where your map will be visualized (cellphones, tablets, or desktops), you might want to consider providing a different width and height:

var height = 600; 
var width = 900; 

The next variable defines a projection algorithm that allows you to go from a cartographic space (latitude and longitude) to a Cartesian space (x, y)—basically...