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 a different status bar CRS than the map

Sometimes, you want to display a different coordinate system for the mouse coordinates in the status bar than what the source data is. With this recipe, you can set a different coordinate system without changing the data.

Getting ready

Download the following zipped shapefile and unzip it to your qgis_data/ms directory:

Also, in your project settings, verify the Enable on the fly projection checkbox is checked.

How to do it...

We will load our layer and then change the destination coordinate system of the map canvas:

  1. First, we will set up the path to the shapefile and load it as a layer:

            pth = "/qgis_data/ms/MSCities_Geo_Pts.shp" 
            lyr = QgsVectorLayer(pth, "Cities", "ogr") 
  2. Then, we add the layer to the map:

  3. Finally, we change the display coordinate system to a different CRS: