Normalizing imports

Often data used in a spatial database is imported from other sources. As such it may not be in a form that is useful for our current application. In such a case, it may be useful to write functions that will aid in transforming the data into a form that is more useful for our application. This is particularly the case when going from flat file formats, such as shapefiles, to relational databases such as PostgreSQL.

Note

A shapefile is a de facto as well as formal standard for the storage of spatial data, and is probably the most common delivery format for vector spatial data. A shapefile, in spite of its name, is never just one file, but a collection of files. It consists of at least *.shp (which contains geometry), *.shx (an index file), and *.dbf (which contains the tabular information for the shapefile). It is a powerful and useful format but, as a flat file, it is inherently nonrelational. Each geometry is associated in a one-to-one relationship with each row in a table...