Splitting a shapefile

Sometimes you need to split a shapefile to break a larger dataset into more manageable sizes, or you want to isolate a specific area of interest. There is a script in the Processing Toolbox that splits a shapefile by attribute. It is very useful, even though it is provided as an example on how to write processing scripts.

Getting ready

We will split a census track shapefile by county. You can download the sample zipped shapefile from the following URL:

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

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

How to do it...

This recipe is as simple as running the algorithm and specifying the file name and data attribute:

1. Start QGIS.

2. From the Plugins menu, select Python Console.

3. Import the processing module:

           import processing 
   

4. Define our data directory as a variable to shorten the processing command:

           pth = "/qgis_data/census/" 
   

5. Finally, run the algorithm:

           processing...