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

Creating tiles from a QGIS map

This recipe creates Internet web map tiles from your QGIS map. What's interesting about this recipe is once the static map tiles are generated, you can serve them up from any web-accessible directory using JavaScript client-side in a browser without the need for a map server.

Getting ready

You will need to download the following zip-shape file from this URL:

Unzip the file to a directory named shapes in your qgis_data directory.

You will also need to install the QMetaTiles plugin using QGIS Plugin Manager.

How to do it...

We will load our shapefile and randomly color each country. We'll then manipulate the QMetaTiles plugin using Python to generate map tiles for five zoom levels, worth of tiles.

  1. First, we need to import all the necessary Python libraries, including the QMetaTiles plugin:

            from PyQt4.QtCore import * 
            from PyQt4.QtGui import * 
            import QMetaTiles