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

Using icons as vector layer symbols

In addition to the default symbol types available in QGIS, you can also use TrueType fonts as map symbols. TrueType fonts are scalable vector graphics that can be used as point markers. In this recipe, we'll create a symbol of this type.

Getting ready

You can download the point shapefile used in this recipe from

Extract it to your qgis_data directory, in a folder named nyc.

How to do it...

We will load a point shapefile as a layer and then use the character G in a freely available font called Webdings, which is probably already on your system, to render a building icon on each point in the layer. To do this, we need to perform the following steps:

  1. First, we'll define the path to our point shapefile:

            src = "/qgis_data/nyc/NYC_MUSEUMS_GEO.shp" 
  2. Then, we'll load the vector layer:

            lyr = QgsVectorLayer(src, "Museums", "ogr") 
  3. Now, we'll use a Python dictionary to define...