create listw-objects from shapefiles

Dear R-sig-geo list,

I would like to do some spatial analyses such as 
moran.test, for which I need a listw. I have 
shapefile data, so I tried to apply the following steps:

-         create spatial polygons with readShapePoly (maptools package)
-         create neighbours list by poly2nb (spdep package)
-         create spatial weights with nb2listw

I get an error message for the last step saying 
that my nb-object is empty but I have results in 
the neigbours list object in the previous step
No, you have two observations with empty sets of neighbours:
2 regions with no links:
44 78
Either fix that - for example with edit.nb(), or accept that this is 
reasonable - they really have no neighbours, and set zero.policy=TRUE.

Roger
Here are my results:

 > lyme <- readShapePoly ("Filename", 
proj4string=CRS(as.character (NA)), verbose=FALSE)

 > summary(lyme)
Object of class SpatialPolygonsDataFrame
Coordinates:
         min      max
r1 22120.69 295156.8
r2 21153.22 244018.8
Is projected: NA
proj4string : [NA]
Data attributes: different attributes

 > lyme_nb <- poly2nb(as(lyme, "SpatialPolygons"))
 > summary(lyme_nb)
Neighbour list object:
Number of regions: 589
Number of nonzero links: 3314
Percentage nonzero weights: 0.9552607
Average number of links: 5.626486
2 regions with no links:
44 78
Link number distribution:

   0   1   2   3   4   5   6   7   8   9  10  11  12  14  15
   2   2  10  35  75 170 144  86  38  17   5   1   2   1   1
2 least connected regions:
8 363 with 1 link
1 most connected region:
73 with 15 links

 > lyme_w <- nb2listw(lyme_nb,glist=NULL,style="W",zero.policy=FALSE)
Error in nb2listw(lyme_nb, glist = NULL, style = "W", zero.policy = FALSE) :
         Empty neighbour sets found

Is there something wrong? Do I miss something? 
Thank you very much for any help!

Catherine

Catherine Linard
University of Louvain
Department of Geography
Place Pasteur, 3
B - 1348 Louvain-la-Neuve
BELGIUM

Tel: +32/10/47.28.67
Fax: +32/10/47.28.77
e-mail: linard at geog.ucl.ac.be

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Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no

create listw-objects from shapefiles

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