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

Experiment 4 – using updates and transitions to enhance our visualization

For our next experiment, we will take all of our combined knowledge and add some smooth transitions to the map. Transitions are a fantastic way to add style and smoothness to data changes.

This experiment will, again, require us to start with example-3.html. The complete experiment can be viewed at http://localhost:8080/chapter-4/example-5.html.

If you remember, we leveraged the JavaScript setInterval() function to execute updates at a regular timed frequency. We will go back to this method now to assign a random number between 1 and 33 to our existing color() function. We will then leverage a D3 method to smoothly transition between the random color changes.

Right below the update section, add the following setInterval() block of code:

    setInterval(function(){
map.selectAll('path&apos...