Greetings Jake,
Give this a try:
-------------------
import ucar.nc2.NetcdfFile;
import ucar.nc2.dataset.NetcdfDataset;
import ucar.nc2.Variable;
import ucar.ma2.*;
import java.io.IOException;
import java.util.ArrayList;
public class OpenDapTst {
public static void main(String args[]) {
try{
NetcdfFile ncfile =
NetcdfDataset.openFile("http://nomads.ncdc.noaa.gov/thredds/dodsC/ruc13/201110/20111018/ruc2_130_20111018_1300_000.grb2";,
null);
Variable v = ncfile.findVariable("Temperature");
Array data = null;
try {
//
// This is the magic you are looking for!
//
data = v.read("0,2,100,300");
} catch (InvalidRangeException e) {
e.printStackTrace(); //To change body of catch statement use
File | Settings | File Templates.
}
//
// The following two lines are the proper way
// to index into the array
//
//Index idx = data.getIndex();
//float val = data.getFloat(idx.set0(0));
//
// The following line will do the trick if you know that you
// will be getting a scalar back
//
float val = data.getFloat(0);
System.out.format("The value of val is: %f%n", val);
} catch (IOException e) {
e.printStackTrace();
}
}
}
-------------------
Let me know if this works for you. Cheers!
Sean
On Fri, 21 Oct 2011, John Caron wrote:
> Hi Jake:
>
> Look at
>
> http://www.unidata.ucar.edu/software/netcdf-java/tutorial/NetcdfFile.html
> http://www.unidata.ucar.edu/software/netcdf-java/tutorial/NetcdfDataset.html
>
> especially the "Reading Data" in the first.
>
> The only difference for opendap is using NetcdfDataset.openFile()
> instead of NetcdfFile.open(), eg:
>
> NetcdfDataset.openFile("http://nomads.ncdc.noaa.gov/thredds/dodsC/ruc13/201110/20111018/ruc2_130_20111018_1300_000.grb2";,
> null);
>
> John
>
> On 10/20/2011 9:17 PM, Jake Sheck wrote:
> > UCAR NetCDF mail group,
> >
> > I am working on acquiring small amounts of GFS, NAM and RUC data from
> > nomads.ncdc.noaa.gov. As a test I am trying to collect the Temperature
> > variable for a particular point. I can easily acquire this data via my web
> > browser with this link.
> > http://nomads.ncdc.noaa.gov/thredds/dodsC/ruc13/201110/20111018/ruc2_130_20111018_1300_000.grb2.asc?Temperature[0][2][100][300]
> >
> > I would like to collect this variable via the netcdf java library. However
> > I can't seem to find documentation on the correct use of the dimensions
> > variables in the readSection or readArrays methods of the DODSNetcdfFile.
> > Could anyone please direct me to documentation for these? I have found
> > that even when I specifiy dimenions for a variable it still downloads the
> > complete grid and takes much longer than the link above.
> >
> > Here is an example of what I am trying to do.
> >
> > String modelFile =
> > "http://nomads.ncdc.noaa.gov/thredds/dodsC/ruc13/201110/20111018/ruc2_130_20111018_1300_000.grb2";;
> > DODSNetcdfFile ncfile = new DODSNetcdfFile( modelFile );
> >
> > Dimension time = new Dimension("time", 1);
> > Dimension pressure = new Dimension("pressure",1);
> > Dimension xd = new Dimension("x", 126);
> > Dimension yd = new Dimension("y", 557);
> >
> > List<Dimension> ds = new ArrayList<Dimension>();
> > ds.add(time);
> > ds.add(pressure);
> > ds.add(xd);
> > ds.add(yd);
> >
> > for(Variable v : ncfile.getVariables()){
> > if(v.getName.equals("Temperature_height_above_ground"))
> > preloadVariables.add(v);
> > }
> >
> >
> > List<Array> arrays = ncfile.readArrays( preloadVariables );
> >
> > Here I get the variable for temperature, but I get the whole set, and not a
> > set limited by the dimensions that I set.
> >
> > Thanks
> > Jacob Sheck
> >
> >
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