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

Creating a common extent for rasters

If you are trying to compare two raster images, it is important that they have the same extent and resolution. Most software packages won't even allow you to attempt to compare images if they don't have the same extent. Sometimes, you have images that overlap but do not share a common extent and/or are of different resolutions. The following illustration is an example of this scenario:

In this recipe, we'll take two overlapping images and clip them to the common extents.

Getting ready

You can download two overlapping images from

Unzip the images and place them in your /qgis_data/rasters directory.

You will also need to download the processing script from the following link:

Unzip the contents and place the scripts in your \.qgis2\processing\scripts directory, found within your user directory. For example, on a Windows 64...