Book Image

Learning QGIS - Third Edition

By : Anita Graser
Book Image

Learning QGIS - Third Edition

By: Anita Graser

Overview of this book

QGIS is a user-friendly open source geographic information system (GIS) that runs on Linux, Unix, Mac OS X, and Windows. The popularity of open source geographic information systems and QGIS in particular has been growing rapidly over the last few years. Learning QGIS Third Edition is a practical, hands-on guide updated for QGIS 2.14 that provides you with clear, step-by-step exercises to help you apply your GIS knowledge to QGIS. Through clear, practical exercises, this book will introduce you to working with QGIS quickly and painlessly. This book takes you from installing and configuring QGIS to handling spatial data to creating great maps. You will learn how to load and visualize existing spatial data and create data from scratch. You will get to know important plugins, perform common geoprocessing and spatial analysis tasks and automate them with Processing. We will cover how to achieve great cartographic output and print maps. Finally, you will learn how to extend QGIS using Python and even create your own plugin.
Table of Contents (13 chapters)
Learning QGIS Third Edition
About the Author
About the Reviewer

Getting to know the Python Console

The most direct way to interact with the QGIS API (short for Application Programming Interface) is through the Python Console, which can be opened by going to Plugins | Python Console. As you can see in the following screenshot, the Python Console is displayed within a new panel below the map:

Our access point for interaction with the application, project, and data is the iface object. To get a list of all the functions available for iface, type help(iface). Alternatively, this information is available online in the API documentation at

Loading and exploring datasets

One of the first things we will want to do is to load some data. For example, to load a vector layer, we use the addVectorLayer() function of iface:

v_layer = iface.addVectorLayer('C:/Users/anita/Documents/Geodata/qgis_sample_data/shapefiles/airports.shp','airports','ogr')

When we execute this command, airports.shp will be loaded using the ogr driver...