[R-sig-Geo] Merging separate polygons in administrative entities

[Paul Hewson]

Hello,
 
I've imported a file from ArcView which should contain around 300 administrative entities.   However, I have over 600 polygons, mainly because of islands.  I can do mapping and so on by using the merge command.
 
Is there a way of rearranging the data so that islands etc. are associated with the adminstrative entity.   I want to do neighouring (poly2nb) and I get a lot of blank entries because all the islands are seen as distinct entities, whereas they should presumably only be 300 $shapes in the polylist?
 
I assume this may have arisen because of the way I handled the data in ArcView.
 
Thanks for any help
 
Paul Hewson
Lecturer in Statistics
University of Plymouth