Learn QGIS - Fourth Edition

Creating a memory layer

A great way to create a temporary vector layer is by using so-called memory layers. Memory layers are a good option for temporary analysis output or visualizations. They are the scripting equivalent of temporary scratch layers, which we used in Chapter 2, Data Creation and Editing. Like temporary scratch layers, memory layers exist within a QGIS session and are destroyed when QGIS is closed. In the following example, we create a memory layer and add a polygon feature to it.

Basically, a memory layer is a QgsVectorLayer like any other. However, the provider (the third parameter) is not ogr as in the previous example of loading a file, but memory. Instead of a file path, the first parameter is a definition string that ...