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
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Filtering a layer by geometry

In this recipe, we'll perform a spatial operation to select the subset of a point layer based on the points contained in an overlapping polygon layer. We'll use shapefiles in both the cases, with one being a point layer and the other a polygon. This kind of subset is one of the most common GIS operations.

Getting ready

We will need two new shapefiles that have not been used in the previous recipes. You can download the point layer from

Similarly, you can download the geometry layer from

Unzip these shapefiles and place them in a directory named ms within your qgis_data directory, within your root or home directory.

How to do it...

In this recipe, we will perform several steps to select features in the point layer that fall within the polygon layer, as follows:

  1. First, load the point layer:

            lyrPts = QgsVectorLayer...