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QGIS Python Programming Cookbook, Second Edition

You're reading from   QGIS Python Programming Cookbook, Second Edition Automating geospatial development

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Product type Paperback
Published in Mar 2017
Publisher Packt
ISBN-13 9781787124837
Length 464 pages
Edition 2nd Edition
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Author (1):
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Joel Lawhead Joel Lawhead
Author Profile Icon Joel Lawhead
Joel Lawhead
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Toc

Table of Contents (10) Chapters Close

Preface 1. Automating QGIS FREE CHAPTER 2. Querying Vector Data 3. Editing Vector Data 4. Using Raster Data 5. Creating Dynamic Maps 6. Composing Static Maps 7. Interacting with the User 8. QGIS Workflows 9. Other Tips and Tricks

Using the __geo_interface__ protocol

The __geo_interface__ is a newer protocol, created by Sean Gillies and targeted mainly at Python, to provide a string representation of geographical data following Python's built-ins protocol. The string representation for geographical data is basically GeoJSON. You can read more about this protocol here:

https://gist.github.com/sgillies/2217756

Two developers, Nathan Woodrow and Martin Laloux, refined a version of this protocol for QGIS Python data objects. This recipe borrows from their examples to provide a code snippet, which you can put at the beginning of your Python scripts to retrofit QGIS feature and geometry objects with a __geo_interface__ method.

Getting ready

This recipe requires no preparation.

How to do it...

We will create two functions: one for features and one for geometry. We'll then use Python's dynamic capability to patch the QGIS objects with a __geo_interface__ built-in method.

  1. First, we'll need the Python json module...
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