
 
Dear list,
I've used R for simple statistics in the past, but this is my first attempt at manipulating spatial data. The transition is frustrating and I'd appreciate any advice you can give me on the problem below. 
 
I'm creating interpolated surfaces of PCA loadings extracted from some precipitation data in Oregon/WA USA. I'm using the package fields. I can create the interpolated surface, but I need to use the data from the interpolated surface, either extracting values from the surface for specific x,y locations, or exporting the surface to an ascii grid file, or some format that I can either access via another R package (rgdal??) or ArcGIS, which I've used in the past. 
 
I'd be very grateful for suggestions and/or a snippet of example code telling me how to make the interpolated surface created below, into a spatial object that I can analyze further. 
 
Thanks in advance,
 
Zack
 
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require(fields)
require(maptools)
require(sp)

data <- readShapePoints("C:/climate_data/pnw_data/climate_PNW_PCLOAD.shp",   # read in shapefile with X,Y and PC loadings for climate stationsproj4string=CRS(as.character(NA)), verbose=FALSE)
 data <- as.data.frame(data)   long <- x[,1] # longitude column lat <- x[,2]   # latitude column minlat <- min(lat)  maxlat <- max(lat) minlong<- min(long) maxlong <- max(long)  grid.l<- list( X1= seq( minlong,maxlong,,100), X3=seq(minlat,maxlat,,100))  # create grid.list object using ranges of Long. and Lat.  make.surface.grid(grid.l)  y <- data$pc1                   # Princ. Comp. loading I want to interpolate LL <- cbind(long,lat)           # combine Lat and Long fit = Krig(LL,y, theta = 10)   # fit Princ. comp. 1 to Lat long.  surface( fit, grid.list=grid.l)   # create interpolated surface based on Krig object
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