[R-sig-Geo] Problem with aggregating UScensus2000 FL data

[Ista Zahn]

Hi all,
I am trying to aggregate the UScensus data for Florida up to the zip
code level using unionSpatialPolygons from the maptools package. This
works for other states, but not for Florida:

## Works
tmp <- county(fips = gsub("^..", "",
countyfips$fips[countyfips$acronym == "fl"]), state = "fl", level =
"tract")
dat <- as.data.frame(tmp)
tmp.county <- unionSpatialPolygons(tmp, dat$county)

## Returns error
tmp <- county(fips = gsub("^..", "",
countyfips$fips[countyfips$acronym == "al"]), state = "al", level =
"tract")
dat <- as.data.frame(tmp)
tmp.county <- unionSpatialPolygons(tmp, dat$county)
Error in TopologyFunc(groupID(spgeom[ids[[i]]], id[ids[[i]]]),
names(ids)[i],  :
  TopologyException: found non-noded intersection between LINESTRING
(-0.640183 0.433522, -0.678743 0.433456) and LINESTRING (-0.678743
0.433456, -0.677839 0.434367) at -0.678743 0.433456

Does anyone have a suggestion about how to do this?

Thanks!

Ista
-- 
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org