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

Clipping a raster using a shapefile

Sometimes, you need to use a subset of an image which covers an area of interest for a project. In fact, areas of an image outside your area of interest can distract your audience from the idea you are trying to convey. Clipping a raster to a vector boundary allows you to only use the portions of the raster you need. It can also save processing time by eliminating areas outside your area of interest.

Getting ready

We will use the SatImage raster again, available at the following URL if you haven't downloaded it from the previous recipes:

Place this raster in your /qgis_data/rasters directory.

How to do it...

Clipping is a common operation and GDAL is well suited for it. Perform the following steps:

  1. First, in the QGIS Python Console, import the processing module:

            import processing 
  2. Next, run the processing command specifying the input image name as the second argument and the output image...