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

Making a hexbin map

Having improved our US state choropleth map with hexagons, let’s now use hexagons to alter our dot density map. There are benefits to a dot density map as we have seen previously, so the changes we are about to make are more alterations than clear improvements. Here’s what we will build:

A map of many hexagons in color

It’s a hexbin map showing the farmers' markets hotspots. Areas with no farmers' markets are shown as white hexagons, areas with many farmers' markets are shown in blue to dark purple. Lighter and less saturated yellow and green hexagons represent areas with fewer markets.

Reviewing the hexbin algorithm

What do we want to achieve? There are two major steps...