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
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Creating inverted polygon shapeburst fills


Shapeburst fills are a type of symbol layer that allows you to create buffered gradient fills. They are commonly used to shade water features in a realistic fashion, using different hues of blue to simulate water depth changes. In this recipe, we'll do exactly that. We'll use a land shapefile and a water shapefile, and in the water feature, we'll color it a darker blue toward the middle and lighter blue toward the edges to give the illusion of deeper water in the middle.

Getting ready

Download the following zipped set of shapefiles. Extract them into a directory named hancock in your qgis_data directory:

https://github.com/GeospatialPython/Learn/raw/master/hancock_land_water.zip.

How to do it...

We will create our layers for the land and water shapefiles. Then, we'll set up a fill symbol for the land layer. Next we'll set up the shapeburst fill for the water. Finally, we'll add those layers to the map to view them:

  1. First, we need to import the PyQt GUI...