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

Adding labels to a map for printing

The QgsComposition object allows you to place arbitrary text anywhere in the composition. In this recipe, we'll demonstrate how to add a label to a map composition.

Getting ready

You will need to download the following zipped shapefile and extract it to your qgis_data directory in a subdirectory named hancock:

In addition to the shapefile, you will also need the MapComposer class. This class encapsulates the boilerplate composer code in a reusable way, to make adding other elements easier. You can download it from

This file must be accessible from the QGIS Python console by ensuring that it is in the Python path directory. Place the file in the .qgis2/python directory within your home directory.

How to do it...

To add a label to a composition, we'll first build the map composition, create a label, and then save the composition...