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

Running QGIS scripts as scheduled tasks

The theme of this book is using PyQGIS to automate QGIS to transform it from a desktop application into a framework. Most of the time, when you are automating a process, you do so because you want to repeat that workflow over and over again. If the workflow is fairly static, with only a few simple variables, you can even automate running that task on a schedule. In this recipe, we'll automate downloading some precipitation data, and clipping it to a political boundary. Then, we'll set up that process to run automatically on a periodic basis.

Getting ready

We'll be creating a standalone QGIS script. So, you'll need to create a Python file and open it in a text editor.You will also need to install the Python pytz and schedule modules, both available on PyPI. Finally, you'll need to download the following zipped shapefile and extract it to a directory named ms in you qgis_data directory: