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 checkboxes

Checkboxes are closely related to radio buttons, in that they offer options around a single theme. However, unlike radio buttons, checkboxes can be selected or unselected. You can also select more than one checkbox at a time. In this recipe, we'll create a dialog with checkboxes and some textboxes to programmatically track which checkboxes are selected.

Getting ready

Open the QGIS Python console by selecting the Plugins menu and then clicking on Python Console.

How to do it...

In this recipe, we'll use a class to manage the checkboxes and the textbox widgets, as follows:

  1. First, we import the GUI and QGIS core libraries:

            from PyQt4.QtCore import * 
            from PyQt4.QtGui import * 
  2. Next, we create our custom class for the checkboxes and textboxes:

            class CheckBox(QWidget): 
                def __init__(self, parent=None): 
                    QWidget.__init__(self, parent) 
  3. Next, we'll need a layout object to manage the placement of the widgets...