Hi Robert, Thank you so much for your help. It works very nicely .... i wonder why the extension was grd .... nowhere on the site from where i downloaded the data it said it is a netCDF file .... Monica
> Date: Wed, 28 Jan 2009 09:58:23 +0800 > Subject: Re: [R-sig-Geo] reading *.grd files - revisited > From: r.hijm...@gmail.com > To: pisican...@hotmail.com > CC: r-sig-geo@stat.math.ethz.ch > > Dear Monica, > > You probably refer to this thread: > https://stat.ethz.ch/pipermail/r-sig-geo/2008-October/004326.html > which is about Surfer (.grd) files. Unfortunately .grd is used for > many different formats, and your file is not a Surfer .grd file. > > In fact it is a netCDF file. ( .cdf or .nc are more common extensions > for that format !) > > I was able to read your file and plot the values like this (I use the > raster package, but you can adapt the last bit if you do not want > that): > > # you probably need to install these two packages: > install.packages("ncdf") > install.packages("raster", repos="http://R-Forge.R-project.org") > > require(ncdf) > require(raster) > > f <- "d:/test_grid.grd" > nc <- open.ncdf(f) > xr <- get.var.ncdf(nc, nc$var[[1]]) > yr <- get.var.ncdf(nc, nc$var[[2]]) > res <- get.var.ncdf(nc, nc$var[[4]]) > dims <- get.var.ncdf(nc, nc$var[[5]]) > v <- as.vector(get.var.ncdf(nc, nc$var[[6]])) > close.ncdf(nc) > > xm <- xr[1] - 0.5 * res[1] > xx <- xr[2] + 0.5 * res[1] > ym <- yr[1] - 0.5 * res[2] > yx <- yr[2] + 0.5 * res[2] > > r <- newRaster(xmn=xm, xmx=xx, ymn=ym, ymx=yx, ncols=dims[1], nrows=dims[2]) > r <- setValues(r, v) > plot(r) > > # if you want an sp grid object > sp <- asSpGrid(r) > > > Robert > > On Wed, Jan 28, 2009 at 12:21 AM, Monica Pisica wrote: >> >> Hi, >> >> I've read already the thread about how to read *.grd files in R. What i want >> to do is to re-save the file in a geotiff format so i can load it in ArcGIS. >> I tried readRGDAL and i got the following error: >> >> x <- readRGDAL("test_grid.grd") >> Error in .local(.Object, ....): >> GDAL Error 4: "test_grid.grd' not recognized as a suported file format. >> >> Next step was to do what Alexander Brenning suggested using RSAGA but after >> installing the library and trying the following command i got this error: >> >> rsaga.get.usage("io_grid",3) >> >> Error in setwd (env$workspace) : character argument expected >> In addition: warning message: >> In rsaga.env() >> SAGA command line program 'saga.cmd.exe' not found in any of the paths >> c:/PROGRA~2/R/R~28~1.1PA/library/RSAGA/saga_vc >> ..... >> >> Following afterwards a list of directories in my computer. Do i need to >> install any other additional package and load it in order to use RSAGA??? >> >> I receive almost same error for the command >> rsaga.geoprocessor("io_grid",3, param = list(GRID = "temp.sgrd", FILE = >> "test_grid.grd")) >> >> I have installed R 2.8.1 patched and all packages are updated, on a Windows >> XP professional x64 machine 64 bit. >> >> If anybody wants to give it a try you will find the file (probably around >> noon - it takes about 15 - 30 min to upload on the site) at >> ftp://stpfiles.er.usgs.gov/Monica/GRID/test_grid.grd >> >> Thanks for all the help, >> >> Monica >> _________________________________________________________________ >> >> >> 12009 >> _______________________________________________ >> R-sig-Geo mailing list >> R-sig-Geo@stat.math.ethz.ch >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo >> _________________________________________________________________ owitworks_012009 _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo