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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

Deleting a vector layer feature's attribute


In this recipe, we'll remove an entire attribute and all feature fields for a vector layer. Remember, attributes are the column names and fields are the individual values.

Getting ready

You will need the New York City museums shapefile used in other recipes, which you can download as a ZIP file from the following URL:

https://github.com/GeospatialPython/Learn/raw/master/NYC_MUSEUMS_GEO.zip

Extract this shapefile to /qgis_data/nyc.

How to do it...

This operation is straightforward. We'll load and validate the layer, use the layer data provider to delete the attribute by index, and finally update all of the fields to remove the orphaned values:

  1. Start QGIS.

  2. From the Plugins menu, select Python Console.

  3. First, we load and validate the layer:

            vectorLyr=  QgsVectorLayer('/qgis_data/nyc/NYC_MUSEUMS_GEO.shp',
                                       'Museums' , "ogr") 
            vectorLyr.isValid() 
    
  4. Then, we delete the first attribute:

            vectorLyr...
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