Constructing a Geographical Database

TL;DR: The format of the geographical database and the steps involved in constructing one are described, illustrated by the experience in creating a database for the coastlines and national political boundaries of the world.

Abstract: The map() function in S permits a wide range of line and filled area maps to be drawn for use with map-oriented data analysis. The data underlying these maps is stored in a geographical database. This report describes the format of the geographical database and the steps involved in constructing one. The process is illustrated by our experience in creating a database for the coastlines and national political boundaries of the world. The world database allows data to be displayed on a map of the entire world or on smaller subsets such as Europe or individual countries. The data comes from the World Data Bank II (US Dept. of Commerce) but we have performed edits to correct digitizing errors and have added accurate descriptions of the polygonal regions that make up each country. Because the database contains polygonal information, choropleth maps can be drawn that use data values to control the color of regions, and because it is so detailed, maps can be made in a wide range of scales.