Can anyone tell me of an open source where I can get the shapefile for France at a postal code level?
This seems to be what you're looking for.
The translated help file from the ZIP file is below:
BACKGROUND CARD OF POSTAL CODES IN METROPOLITAN FRANCE
This file contains the layout of the postal codes in France (including the supra-communal postal codes) and an estimate of the population and number of households.
This file is from a data processing led by grouping EMC3 several sources of information:
- GEOFLA® Commons produced by IGN (2013 edition)
- HEXAPOSTE produced by the National Service Address (January edition 2014),
- 200 meters gridded data released by INSEE
- Results of the general population census published by INSEE. We thank Nicolas Touyet whose work allowed the development of the base map. Emc3 maintains this data set to improve the accessibility of citizens reference to geographic data. Our goal is to provide information as accurate as possible. If errors are brought to our attention, we try to correct them. However, EMC3 assumes no responsibility the accuracy of information on this set of geographic data.
This particular game is published under license ODbL (for more information visit: http://opendatacommons.org/licenses/odbl/summary/). That means you can distribute, reproduce and enrich this resource as long that you cite the sources.
The geographic data is provided by Lambert projection 93 at ESRI Shape and MapInfo.
id: ID of the 5-digit postal code
lib wording postcode
dep: department code
surf: area (in km²)
pop2010: estimated population in 2010
men2010: estimated number of households in 2010
From the common plot of GEOFLA base and HEXAPOSTE file we have grouped the municipalities belonging to the same postal code. For municipalities subdivided into several zip codes, reverse geocoding and a contour algorithm have afforded the sub-municipal path. The base map obtained provides a route compatible with the base GEOFLA edition 2013.
Estimates of population and number of households were obtained confronting cutting zip codes with gridded data INSEE: the population of a tile having been divided in proportion to the common area to the tile and the different postal codes. An adjustment then performed to allow compatibility with the results of general census of the population.