[R-sig-Geo] Reshaping geographic data

[G.Maubach at weinwolf.de]

Hi All,

I need to reshape an ESRI shape file: http://arnulf.us/PLZ and resp 
http://www.metaspatial.net/download/plz.tar.gz

This means that I need to combine the areas of the ZipCodes (i. e. PLZ) to 
the ZipCode regions (i. e. PLZ Leitregion). 

Example:
The city "Duesseldorf" has a couple of ZipCodes for different parts of the 
city, e. g. 40210 40211 40212 40213 40215 40217 and so on. The ZipCode 
region (PLZ Leitregion) is "40".

What I need to do is to combine the area information in the above given 
ESRI shapefile to get the area for the ZipCode region.

I found an instruction for T-SQL Server:

https://blog.oraylis.de/2010/05/german-map-spatial-data-for-plz-postal-code-regions/

How can I do this using R?

Kind regards

Georg