[R] Plotting data on a map

[phiroc at free.fr]

Hello,

I would like to generate a small map (say 10cm x 10cm) of France showing cumulative numbers by Distribution Center
stored in a database:

DISTRIBUTION_CENTER                 COUNT
Paris                               122
Paris                               3
Paris                               21
Lyon                                12
Lyon                                4444
Lyon                                33
Grenoble                            55
Grenoble                            999
Grenoble                            99
...

I have looked at different graphing packages such as 'sp', 'raster' and 'ggplot2', but am not sure which one is most
appropriate for my purposes. Furthermore, I don't understand how you retrieve city coordinates from shp, gadm, etc., maps
generated, or downloaded from the web and then processed, with those packages (SHP, GADM, etc.), and plot data at those coordinates.

Any help would be much appreciated.

Many thanks.

Philippe