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

Exporting a layer to the GeoPackage format

The GeoPackage format is a developing open standard with recently added support in QGIS. The GeoPackage format has the properties of both the file format and a geodatabase. It overcomes all the limitations of the shapefile format, such as file size limits, attribute name length limits, and many other inconveniences. In a single file, GeoPackages can contain multiple vector and raster datasets. Software can query the file like a database without the overhead of a database server.

Read support for GeoPackages in QGIS is robust; however, write support has some limitations. You can save a single layer to the GeoPackage format using the QgsVectorLayer class or the Processing Toolbox. However, if you want to store multiple layers in a GeoPackage, you must use OGR directly. Fortunately, OGR is included in QGIS and available in the Python Console. In this recipe, we'll load two vector layers and save them in a single GeoPackage using OGR.

Getting ready