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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 (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

Measuring the distance between two points


In the QgsDistanceArea object, PyQGIS has excellent capabilities for measuring the distance. We'll use this object for several recipes, starting with measuring the distance between two points.

Getting ready

If you don't already have the New York City Museums layer used in the previous recipes in this chapter, download the layer from https://github.com/GeospatialPython/Learn/raw/master/NYC_MUSEUMS_GEO.zip.

Unzip that file and place the shapefile's contents in a directory named nyc within your qgis_data directory, within your root or home directory.

How to do it...

In the following steps, we'll extract the first and last points in the layer's point order and measure the distance between them:

  1. First, import the library that contains the QGIS contents:

            from qgis.core import QGis 
    
  2. Then, load the layer:

            lyr = QgsVectorLayer("/qgis_data/nyc/NYC_MUSEUMS_GEO.shp",
                                 "Museums", "ogr") 
    
  3. Access the features:

    ...
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