[R] netCDF to raster and spatial projection

[Frede Aakmann Tøgersen]

Hi Beatriz

Try to skip this step

>      # Reprojecting into CH1903_LV03
>      # First, change the coordinate reference system (crs)
>      proj4string(rasterDF1) <- "+init=epsg:21781"


And just do this

>      # Second, reproject the raster
>      rasterDF1.CH <- spTransform(rasterDF1, crs("+init=epsg:21781"))
>

Also there is a spTransform both in the rgdal and sp packages. So are they masking each other? rgdal should be before sp in the search() list.

I cannot be of more help since you provided no data. 


Yours sincerely / Med venlig hilsen


Frede Aakmann Tøgersen
Specialist, M.Sc., Ph.D.
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> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
> On Behalf Of Beatriz R. Gonzalez Dominguez
> Sent: 16. april 2014 08:22
> To: r-help at r-project.org
> Subject: [R] netCDF to raster and spatial projection
> 
> 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
>      library("sp")
>      library("raster")
>      library("rgdal")
>      library("ncdf")
>      library("maptools")
>      library("rgeos")
>      library("sm")
>      library("chron")
> 
>      # 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
> +towgs84=0,0,0"
> 
> 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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> and provide commented, minimal, self-contained, reproducible code.