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 HTML labels in QGIS

QGIS map tips allow you to hover the mouse cursor over a feature to create a popup that displays information. This information is normally a data field, but you can also display other types of information using a subset of HTML tags. In this recipe, we'll create an HTML map tip that displays a Google Street View image at the feature's location.

Getting ready

In your qgis_data directory, create a directory named tmp.

You will also need to download the following zipped shapefile and place it in your qgis_data/nyc directory:

How to do it...

We will create a function to process the Google data and register it as a QGIS function. Then, we'll load the layer and set its map-tip display field:

  1. First, we need to import the Python libraries we'll need:

            from qgis.utils import qgsfunction 
            from qgis.core import QGis 
            import urllib 
            import os 
  2. Next, we'll...