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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
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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