Creating a vector layer in memory

Sometimes, you need to create a temporary data set for quick output or as an intermediate step in a more complex operation without the overhead of actually writing a file to disk. PyQGIS employs memory layers that allow you to create a complete vector data set, including the geometry, fields, and attributes, virtually. Once the memory layer is created, you can work with it in the same way you would work with a vector layer loaded from disk.

Getting ready

This recipe entirely runs inside the PyQGIS console, so no preparation or external resources are required.

How to do it...

We will create a Point vector layer, named Layer 1 with a few fields and then validate it:

1. Start QGIS.
2. From the Plugins menu, select Python Console.
3. In the Python console, create a QgsVectorLayer, including fields, and specify it as a memory data provider:

   vectorLyr =  QgsVectorLayer('Point?crs=epsg:4326&field=city:string(25)&field=population:nt', 'Layer 1' , &quot...