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

Loading data from a spreadsheet

Spreadsheets are one of the most common methods used to collect and store simple geographic data. QGIS can work with text files called Comma Separated Value (CSV) files. Any spreadsheet can be converted to a CSV using the spreadsheet program. As long as the CSV data has a column representing x values, one column representing y values, and other columns representing data with the first row containing field names, QGIS can import it. Many organizations distribute geographic information as a CSV, so sooner or later, you will find yourself importing a CSV. Moreover, PyQGIS lets you do it programmatically. Note that a CSV can be delimited by any character as long as it is consistent. Also, the file extension of the CSV file doesn't matter as long as you specify the file type for QGIS.

Getting ready

We'll use a sample CSV file with point features representing points of interest in a region. You can download this sample from