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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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Table of Contents (16) Chapters Close

QGIS Python Programming Cookbook - Second Edition
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
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

Calculating the bearing of a line


Sometimes, you need to know the compass bearing of a line to create specialized symbology or to use as input in a spatial calculation. Even though its name only mentions distance and area, the versatile QgsDistanceArea object includes this function as well. In this recipe, we'll calculate the bearing of the end points of a line. However, this recipe will work with any two points.

Getting ready

We'll use the line shapefile used in Measuring the distance between two points recipe. You can download the shapefile as a .zip file from https://github.com/GeospatialPython/Learn/raw/master/paths.zip.

Unzip the shapefile into a directory named qgis_data/shapes within your root or home directory.

How to do it...

The steps to be performed are as simple as getting the two points we need and running them through the bearing function, converting from radians to degrees, and then converting to a positive compass bearing:

  1. First, import the Python math module:

            import math...
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