Sorry I take that back, I was using the (independent of GDAL) shapefile reader in maptools. Using the rgdal package, we get the full projection information from the auxiliary .xml file that ships with the other shapefile files.
library(rgdal) ## Here my working directory "." contains "NA_CEC_Eco_Level3.shp" x <- readOGR(".", "NA_CEC_Eco_Level3") OGR data source with driver: ESRI Shapefile Source: ".", layer: "NA_CEC_Eco_Level3" with 2548 features and 11 fields Feature type: wkbPolygon with 2 dimensions summary(x) Object of class SpatialPolygonsDataFrame Coordinates: min max x -4334052 3324076 y -3313739 4267265 Is projected: TRUE proj4string : [+proj=laea +lat_0=45 +lon_0=-100 +x_0=0 +y_0=0 +a=6370997 +b=6370997 +units=m +no_defs] Data attributes: NA_L3CODE ... So, now we can do this: library(maps) require(rgdal) map("state", col = "aliceblue", fill = TRUE, lwd = 2) plot(spTransform(x, CRS("+proj=longlat +ellps=WGS84")), add = TRUE) (Clearly I should have taken this to R-Sig-Geo some time ago). Cheers, Mike. On Sun, Apr 1, 2012 at 6:09 PM, Michael Sumner <mdsum...@gmail.com> wrote: > There is no coordinate system defined for these files- proj4string is > NA, see below - otherwise transforming them to that used by the maps > package is trivial. I suggest you find out the coordinate system from > the provider of the data and ask any further questions on R-Sig-Geo. > This is a big file, ~34 Mb and you should warn people of that. > > library(maptools) > x <- readShapeSpatial("NA_CEC_Eco_Level3.shp") > > summary(x) > Object of class SpatialPolygonsDataFrame > Coordinates: > min max > x -4334052 3324076 > y -3313739 4267265 > Is projected: NA > proj4string : [NA] > Data attributes: > NA_L3CODE NA_L3NAME > 8.5.2 : 217 Mississippi Alluvial Plain : 217 > 7.1.5 : 208 Coastal Western Hemlock-Sitka Spruce Forests: 208 > 8.5.1 : 163 Middle Atlantic Coastal Plain : 163 > 8.5.3 : 147 Southern Coastal Plain : 147 > 2.1.5 : 135 Foxe Uplands : 135 > 8.1.8 : 98 Acadian Plains and Hills : 98 > (Other):1580 (Other) :1580 > ... > > > > On Sun, Apr 1, 2012 at 4:55 PM, Michael Sumner <mdsum...@gmail.com> wrote: >> Try the R-Sig-Geo mailing list for a better target community, but if these >> are shapefiles there is read support in rgdal (or maptools for a simpler >> alternative) and if these are in long-lat like the maps package then plot(x, >> add=TRUE) will be most of the way there. >> >> If you need to transform either layer then see spTransform or project in >> rgdal. >> >> Cheers, Mike >> >> >> On Sunday, April 1, 2012, chuck.01 wrote: >>> >>> Hi, >>> I want to use map("state") and have the ecoregion shape (please see link) >>> file projected onto this. >>> >>> ftp://ftp.epa.gov/wed/ecoregions/cec_na/NA_CEC_Eco_Level3.zip >>> ftp://ftp.epa.gov/wed/ecoregions/cec_na/NA_CEC_Eco_Level3.zip >>> >>> Could someone please show me how; I have never messed with this sort of >>> thing. >>> Thanks. >>> >>> -- >>> View this message in context: >>> http://r.789695.n4.nabble.com/map-and-shapefile-help-tp4522794p4522794.html >>> Sent from the R help mailing list archive at Nabble.com. >>> >>> ______________________________________________ >>> R-help@r-project.org mailing list >>> https://stat.ethz.ch/mailman/listinfo/r-help >>> PLEASE do read the posting guide >>> http://www.R-project.org/posting-guide.html >>> and provide commented, minimal, self-contained, reproducible code. >> >> >> >> -- >> Michael Sumner >> Institute for Marine and Antarctic Studies, University of Tasmania >> Hobart, Australia >> e-mail: mdsum...@gmail.com > > > > -- > Michael Sumner > Institute for Marine and Antarctic Studies, University of Tasmania > Hobart, Australia > e-mail: mdsum...@gmail.com -- Michael Sumner Institute for Marine and Antarctic Studies, University of Tasmania Hobart, Australia e-mail: mdsum...@gmail.com ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.