Walt, You should be able to read and plot this file like this:
library(raster) b = brick("air.mon.mean.nc", varname= 'air') plot(b, 1) #or r = raster("air.mon.mean.nc", varname= 'air', band=1) plot(r) #or sp = as(b, 'SpatialGridDataFrame') #etc The projection info is stored in r...@prj (for the time being, util I transform these to proj4 syntax, for at the least the common cases) Robert On Wed, Jul 14, 2010 at 10:42 AM, Walt Golet <wgo...@gmri.org> wrote: > Hello, > A new list member here with a question regarding the display of projected > NetCDF files in R. The initial grids (dimension 349 x 277) cover all of > North America with the following borders: > 12.2N;133.5W, 54.5N; 152.9W, 57.3N; 49.4W ,14.3N;65.1W in the Lambert > Conformal Conic Grid. I extracted a smaller grid (our area of interest) > which becomes a 64 x 51 matrix for air temperature, longitude and latitude > with new borders (40.614, -84.052) (54.263, -76.513) (44.268,-52.644) > (32.869,-63.768). > > #####Reading, extracting and sub setting the grid > library(ncdf) > AIR1=open.ncdf("air.mon.mean.nc",write=FALSE,readunlim=TRUE) > print(AIR1) > AIR2=AIR1$var[[2]] > > AIR=get.var.ncdf(AIR1,AIR2,start=c(1,1,13,1),count=c(349,277,1,372)) > AIR_JAN_1979=AIR[234:297,120:170,1] > AIR2LAT=AIR1$var[[3]] > > AIR_LAT_19791=get.var.ncdf(AIR1,AIR2LAT,start=c(1,1),count=c(349,277)) > AIR_LAT_1979=AIR_LAT_19791[234:297,120:170] > AIR2LONG=AIR1$var[[4]] > > AIR_LONG_19791=get.var.ncdf(AIR1,AIR2LONG,start=c(1,1),count=c(349,277)) > AIR_LONG_1979=AIR_LONG_19791[234:297,120:170] > > #######file information on projection and orientation of grid > int Lambert_Conformal[] " > grid_mapping_name: lambert_conformal_conic" > standard_parallel: 50" " standard_parallel: 50" > longitude_of_central_meridian: -107" > latitude_of_projection_origin: 50" > false_easting: 5632642.22547" > false_northing: 4612545.65137" > y Size:277" #### Original size of grid, extracted one is only 64 x 51 > long_name: northward distance from southwest corner of domain in > projection coordinates" > units: m" > standard_name: projection_y_coordinate" > x Size:349" > long_name: eastward distance from southwest corner of domain in > projection coordinates" > units: m" > standard_name: projection_x_coordinate" > nbnds Size:2" > > > simple plots such as filled.contour will plot the results, but are not > projected properly. > I imagine there is a method within rgdal{spTransform} to correctly display > this data in its projected format or perhaps transform these positions, but > it eludes me at this time. Somewhat similar questions have appeared online, > but the answers I have found do not give correct projections. Any help with > this would be appreciated. Thanks in advance for what may be a simple > transformation, > > Walt > > _______________________________________________ > 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