Issues importing BIG shapefile - Limitations of R or something else?
On Fri, 27 Mar 2009, Tyler Dean Rudolph wrote:
I have no trouble importing a subset of a road network for my study area as a shapefile into R, but when I try to import the complete network (area equivalent to approximately 30,000 km^2), I get the following error message (even when I split up the two class formats into two separate commands):
fullroads<-as(as(readShapeLines(fn="D:\\GIS\\roadnet.shp"),
"SpatialLines"), "psp") *Error in function (classes, fdef, mtable) : unable to find an inherited method for function "coordinates", for signature "numeric"* ** Is this due to the memory limitations of R, or to those of my particular machine, or to something else I'm missing?
It may be the file, it isn't memory (the error message would say so), and it is unlikely to be your machine. Please provide sessionInfo() and traceback() from immediately after the error. If the files in question can be made available as a zip archive on a website, this may allow others to try to debug the problem. We saw something like this with odd polygon geometries recently, but not with lines. Roger
The processes I am trying to model are happening at very "large" spatial scales and it would be a great deal more efficient if I could use the entire road network rather than dealing with multiple subsets of a greater image. Importing as an ascii grid is not an option due to subsequent operations using distmap() which are based on the psp format. Tyler [[alternative HTML version deleted]]
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Roger Bivand Economic Geography Section, Department of Economics, Norwegian School of Economics and Business Administration, Helleveien 30, N-5045 Bergen, Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43 e-mail: Roger.Bivand at nhh.no