Vector structure

To describe the QgsVectorLayer class, we will first approach basic layer parameters, and then we will explore how the vector is organized. We will explore some classes that are involved in the vector structure, which represent rows and headers.

The basic vector methods

We will explore the vector class working on a real vector; we will load alaska.shp in the myVector variable.

This variable is an instance of the QgsVectorLayer class. This means that all methods of the vector are documented at http://qgis.org/api/classQgsVectorLayer.html. As for rasters, this class is a specialization of the generic QgsMapLayer class.

To get the extent of the layer, it's necessary to use the extent() method of the QgsMapLayer class:

print myVector.extent().toString()

Executing the preceding code will generate the following result:

-7115212.9837922714650631,1368239.6063178631011397 : 4895579.8114661639556289,7805331.2230994049459696

This shows the corner coordinates in the format xmin,ymin:...