Creating a complex vector layer symbol

The true power of QGIS symbology lies in its ability to stack multiple symbols in order to create a single complex symbol. This ability makes it possible to create virtually any type of map symbol you can imagine. In this recipe, we'll merge two symbols to create a single symbol and begin unlocking the potential of complex symbols.

Getting ready

For this recipe, we will need a line shapefile, which you can download and extract from https://geospatialpython.googlecode.com/svn/paths.zip.

Add this shapefile to a directory named shapes in your qgis_data directory.

How to do it…

Using the QGISPythonConsole,we will create a classic railroad line symbol by placing a series of short, rotated line markers along a regular line symbol. To do this, we need to perform the following steps:

1. First, we load our line shapefile:

   lyr = QgsVectorLayer("/Users/joellawhead/qgis_data/shapes/paths.shp", "Route", "ogr")
   

2. Next, we get the symbol list and reference the default symbol...