Generalizing a vector layer

Generalizing geometry, also known as simplifying, removes points from a vector layer to reduce the space required to store the data. Otherwise, simplification may result in small but acceptable changes within a specified tolerance.

Getting ready

For this recipe, we will use a boundary file for the state of Mississippi, which you can download from the following URL:

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

Extract the zipped shapefile to a directory named /qgis_data/ms.

How to do it...

Generalizing is native to QGIS, but we will access it in PyQGIS through the Processing Toolbox using the qgis:simplifygeometries algorithm.

1. Start QGIS.

2. From the Plugins menu, select Python Console.

3. Import the processing module:

           import processing 
   

4. Now, we run the processing algorithm specifying the algorithm name, the input data, a tolerance value spacing between points, and the output dataset name:

           processing.runandload("qgis:simplifygeometries...