Mapnik concepts
In this section, we will examine the Python interface to the Mapnik toolkit in more detail. Since there are too many features to cover in their entirety, we will concentrate on the most important aspects of Mapnik that you are likely to use in your own programs. Feel free to refer to the Mapnik documentation (http://mapnik.org/docs) for anything not covered in this chapter.
Data sources
A data source object acts as a "bridge" between Mapnik and your geospatial data. You typically create the data source using one of the following convenience constructors and then add that data source to any Mapnik Layer objects that use that data:
layer.datasource = datasource
There are many different types of data sources supported by Mapnik, though some are experimental or access data in commercial databases. Let's take a closer look at the types of data sources you are most likely to find useful.
Shapefile
It is easy to use a shapefile as a Mapnik data source. All you need to do is supply the...
