Book Image

QGIS Python Programming Cookbook, Second Edition - Second Edition

By : Joel Lawhead
Book Image

QGIS Python Programming Cookbook, Second Edition - Second Edition

By: Joel Lawhead

Overview of this book

QGIS is a desktop geographic information system that facilitates data viewing, editing, and analysis. Paired with the most efficient scripting language—Python, we can write effective scripts that extend the core functionality of QGIS. Based on version QGIS 2.18, this book will teach you how to write Python code that works with spatial data to automate geoprocessing tasks in QGIS. It will cover topics such as querying and editing vector data and using raster data. You will also learn to create, edit, and optimize a vector layer for faster queries, reproject a vector layer, reduce the number of vertices in a vector layer without losing critical data, and convert a raster to a vector. Following this, you will work through recipes that will help you compose static maps, create heavily customized maps, and add specialized labels and annotations. As well as this, we’ll also share a few tips and tricks based on different aspects of QGIS.
Table of Contents (16 chapters)
QGIS Python Programming Cookbook - Second Edition
About the Author
About the Reviewer
Customer Feedback

Performing nearest neighbor analysis

Nearest neighbor analysis relates one point to the nearest point in one or more datasets. In this recipe, we'll relate one set of points to the closest point from another dataset. In this case, we'll find the closest major city for each entry in a catalog of unidentified flying object (UFO) sightings from the National UFO reporting center. This analysis will tell you which major cities have the most UFO activity. The UFO catalog data just contains latitude and longitude points, so we'll use nearest neighbor analysis to assign names to places.

Getting ready

Download the following ZIP file and extract it to a directory named ufo in your qgis_data directory:

You will also need the mmqgis plugin:

  1. From the QGIS Plugins menu, select Manage and Install Plugins....

  2. In the Plugins dialog search box, search for mmqgis.

  3. Select the mmqgis plugin and click on the Install plugin button.

How to do it...

This recipe...