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

Using OpenStreetMap points of interest in QGIS

OpenStreetMap has an API called Overpass that lets you access OSM data dynamically. In this recipe, we'll add some OSM tourism points of interest to a map.

Getting ready

You will need to use the QGIS plugin manager to install the QuickOSM plugin.

You will also need to download the following shapefile and unzip it to your qgis_data/ms directory:

How to do it...

We will load our base layer that defines the area of interest. Then, we'll use the Processing Toolbox to build a query for OSM, download the data, and add it to the map:

  1. First, we need to import the processing module:

            import processing 
  2. Next, we need to load the base layer:

            lyr = QgsVectorLayer("/qgis_data/ms/MSCoast_geo.shp",
                                 "MS Coast", "ogr") 
  3. Then, we'll need the layer extent for the processing algorithms:

            ext = lyr.extent() 
            w =  ext.xMinimum...