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 radio buttons

Radio buttons are good for user input when you want the user to select an exclusive choice from a list of options, as opposed to checkboxes, which let a user select many or all the options available. For a longer list of choices, a combobox is a better option. Once a radio button is selected, you can unselect it only by choosing another radio button.

Getting ready

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

How to do it...

Radio buttons are easier to manage as part of a class, so we'll create a custom class that also includes a textbox to view which radio button is selected. To do this, perform the following steps:

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

            from PyQt4.QtCore import * 
            from PyQt4.QtGui import * 
  2. Next, we'll create the RadioButton class and set up the radio buttons and the textbox:

            class RadioButton(QWidget): 
                def __init__(self, parent=None...