[R] netCDF to raster and spatial projection

Beatriz R. Gonzalez Dominguez aguitatierra at hotmail.com
Wed Apr 16 08:22:00 CEST 2014

I've recently started using R for spatial data. I'd be really grateful 
if you could could help me with this. Thanks!

Sorry I don't provide a reproducible example. Please ask me if you have 
any questions about the data.

I've extracted data from a multidimensional netCDF file. This file had 
longitude, latitude and temperature data (for 12 months of a specific year).

 From this netCDF I've got a data frame for January with these 
variables: longitude, latitude, temperature.

With this data frame I've created a raster.

     # Packages

     # Dataframe to raster
     # Create spatial points data frame
     coordinates(tmp.df01) <- ~ lon + lat
     # Coerce to SpatialPixelsDataFrame
     gridded(tmp.df01) <- T
     # Coerce to raster
     rasterDF1 <- raster(tmp.df01)
     > print(tmp.df01)
     class       : SpatialPixelsDataFrame
     dimensions  : 103, 241, 24823, 1  (nrow, ncol, npixels, nlayers)
     resolution  : 0.02083333, 0.02083333  (x, y)
     extent      : 5.739583, 10.76042, 45.73958, 47.88542  (xmin, xmax, 
ymin, ymax)
     coord. ref. : NA
     names       :           TabsM_1
     min values  : -18.1389980316162
     max values  :  2.26920962333679

There is no value for 'coord. ref.'

The projection of the original netCDF was WGS84. So I gave this 
projection to the raster.

     proj4string(rasterDF1) <- "+proj=longlat +datum=WGS84 +ellps=WGS84 

Then, I wanted to reproject my raster to another projection:

     # Reprojecting into CH1903_LV03
     # First, change the coordinate reference system (crs)
     proj4string(rasterDF1) <- "+init=epsg:21781"
     # Second, reproject the raster
     rasterDF1.CH <- spTransform(rasterDF1, crs("+init=epsg:21781"))

At this point I get the following error:

     Error in spTransform(rasterDF1, crs("+init=epsg:21781")) :
       load package rgdal for spTransform methods

But the package rgdal is already uploaded! It must be something wrong in 
the code!

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