This message should have had a more informative subject, and, given its
specialist character, been sent to R-sig-geo, as is recommended on the
Spatial Task View. From initial trials, the file you are using includes far
too much boundary detail, and appears to have been assembled from disparate
state/county maps (Florida is added late, not in sequence). With a malformed
input map intended for display only, you shouldn't be surprised that the
topology is wrong. I'll investigate whether there is a code issue, but the
real problem is the choice of a very inappropriate input map of an object
size of 64Mb for 56 objects, where you do not need all of the coastal
detail.
Roger
Philip A. Viton wrote:
I downloaded a US states+territories shapefile from
http://www.weather.gov/geodata/catalog/national/html/us-state.htm
and unzipped it into my working directory.
Then in R (version 12.2.0 for ms-win32):
library(rgdal) # Version: 0.6-28
library(spdep) # Version: 0.5-24 (loads sp: Version: 0.9-72)
# read in the data
states-readOGR(.,s_01de10)
summary(states)
# now create a neighbors list
states_nb-poly2nb(states)
# create a 0/1 matrix of the neighbors
nb_mat-nb2mat(states_nb,style=B,zero.policy=TRUE)
# add names
nms-as.character(states$NAMES)
# set the matrix names
dimnames(nb_mat)-list(nms,nms)
# now see which states have no neighbors
rowSums(nb_mat)
# it turns out that Florida seems to have zero neighbors.
I then repeated it with
states_nb-poly2nb(states,useC=FALSE)
and this time -- the computation takes a lot longer, of course
--- Florida has 2 neighbors (correctly: AL and GA).
Can anyone tell me what's going wrong here?
Thanks!
Philip A. Viton
City Planning, Ohio State University
275 West Woodruff Avenue, Columbus OH 43210
vito...@osu.edu
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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
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