Book Image

QGIS Python Programming Cookbook

Book Image

QGIS Python Programming Cookbook

Overview of this book

Table of Contents (16 chapters)
QGIS Python Programming Cookbook
About the Author
About the Reviewers

Calculating the bearing of a line

Sometimes, you need to know the compass bearing of a line to create specialized symbology or 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 a previous recipe. You can download the shapefile as a .ZIP file from

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
  2. Next, load the layer:

    lyr = QgsVectorLayer("/qgis_data...