Hi Julie,
Probably you can downloading and installing using rgdal for Mac OS X from this site http://www.kyngchaos.com/software:frameworks ~~~~~~~~~ GDAL * GDAL framework v1.6.3-1 [44.9 MiB] {requires UnixImageIO, GEOS, SQLite3 and PROJ frameworks} * ECW plugin v1.6.2-1 [2.9 MiB] (for any GDAL 1.6.x version) * MrSID plugin v1.6.1-1 [2.9 MiB] (for any GDAL 1.6.x version) * GRASS plugin is now a separate install, available with the GRASS installer. * rgdal 0.6.22-1 - R 2.10 package [1.5 MiB] (for any GDAL 1.6.x version) * rgdal 0.6.18-1 - R 2.9 package [1.4 MiB] (for any GDAL 1.6.x version) ~~~~~~~~~~~~~~~~~ Noli On 12/31/09, alexandre villers <alexandre.vill...@cebc.cnrs.fr> wrote: > Hey Julie, > > The main problem, for what I understood of working with R and spatial > objects, is that you are using the wrong tools to import your data. Maptools > is mostly deprecated for all the import export function with > shapefile/rasters (but still holds interesting ones for other jobs). > You'll have to struggle a bit and get rgdal to work on your Mac ! > http://cran.r-project.org/bin/macosx/ > Once this is done, it will be much easier to do the job. GDAL is a very > powerful, essential tool to import export data to/from R. So get to the help > list for MAC, the forum and check if > - rgdal is compatible for your version of R MAC > - look for all the packages necessary to compile this packages (I couldn't > download and compile rgdal with linux ubuntu because a small package was > missing...). Just check through the documentation which packages are > necessary to compile rgdal with MAC. > > Once this is done, your work will be much more simple > > You will find all the help you need on the rgdal/sp helpfile and on the > Internet. But do not hesitate to ask questions on the list. > > > Best regards and good luck. > > Alex > > PS: I'm pretty sure a R / rgdal /MAC user will help you with this ! > > -----Original Message----- > From: Julie Lee-Yaw <jullee...@yahoo.ca> > To: r-sig-geo@stat.math.ethz.ch > Date: Wed, 30 Dec 2009 15:32:46 -0800 (PST) > Subject: [R-sig-Geo] stuck on importing and projecting shapefiles > > Hi, > I am new to both R and spatial data and am very stuck on what I think should > be a simple analysis. I am trying to do a polygon overlay analysis of two > shapefiles from different sources. Before proceeding to my overlay > functions, I am trying to plot my shapefiles to double check that they line > up properly. In R, I am using PBSmapping and maptools and the following > script: > > ## read in first shapefile using maptools so I can pull out only those > polygons that are labeled "blue" > > s1=readShapePoly("shapefile1") > s1blue=s1[s1$SYMB=="BLUE",] > s1PS=SpatialPolygons2PolySet(sp1blue) > shape1=combinePolys(sp1PS) > attr(shape1,"projection")<-"LL" > > ## read in second shapefile using PBSmapping routine (in this case, I need > to use importShapefile because I have previously modified this function to > import only select polygons from this file > > shape2<-importShapefile("shapefile2", projection="LL") > > ## trying to plot both together: > > plotPolys(shape1) ##produces reasonable looking plot > addPolys(shape2) > > ## I get the following error message > > In .checkProjection(projectionPlot, projectionPoly) : > The data's 'projection' attribute (LL) differs from the > projection of the plot region (NA). > > This leads me to think that the projections are different and thus my > downstream calculations of intersection areas will be off. The first > shapefile is projected and has the following prj file attached: > > PROJCS["Clarke_1866_Lambert_Conformal_Conic",GEOGCS["GCS_Clarke_1866",DATUM["D_Clarke_1866",SPHEROID["Clarke_1866",6378206.4,294.9786982]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Conformal_Conic"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-95.0],PARAMETER["Standard_Parallel_1",49.0],PARAMETER["Standard_Parallel_2",77.0],PARAMETER["Latitude_Of_Origin",49.0],UNIT["Meter",1.0]] > > The second shapefile is unprojected and the metadata indicates: > projection parameters: units: decimal degrees > Datum: North America 1983 > > Since I'm using a MAC and can't figure out how to load rgdal, I have tried > importing both shapefiles into QGIS (a separate GIS program), reprojecting > them and exporting them from there and re-applying my R code but I get the > same error message. Does anyone have any suggestions as to what I might be > doing wrong and how I can get these shapefiles into a common projection so > that I can calculate the area of their intersection? Thanks in advance for > the help! > > > > Alexandre Villers > PhD. Candidate > Team Agripop > CEBC CNRS UPR 1934 > 79360 Beauvoir sur Niort > > Phone: +33 (0)549 099 613 > > > __________ Information from ESET Mail Security, version of virus signature > database 4730 (20091230) __________ > > The message was checked by ESET Mail Security. > http://www.eset.com > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo