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 a North arrow to the map

North arrows are another common cartographic element, found even in ancient maps, which show the orientation of the map relative to either true, grid, or magnetic north. Sometimes, these symbols can be quite elaborate. However, QGIS provides a basic line arrow element that we will use in combination with a map label to make a basic North arrow.

Getting ready

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

In addition to the shapefile, you will also need the MapComposer class, to simplify the code needed to add this one element. If you haven't already used it in a previous recipe, you can download it from

This file must be accessible from the QGIS Python console; for this, you need to ensure that it is in the Python path directory. Place the file...