## Not run:
# require(maptools)
# xx <- readShapePoly(system.file("shapes/sids.shp", package="maptools")[1],
# IDvar="FIPSNO", proj4string=CRS("+proj=longlat +ellps=clrk66"))
# row.names(as(xx, "data.frame"))
# xx1 <- spChFIDs(xx, as.character(xx$CNTY_ID))
# row.names(as(xx1, "data.frame"))
# ## End(Not run)
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