Re: [netcdf-java] reading grib files

[Robb Kambic <rkambic@xxxxxxxxxxxxxxxx>]

Chad,

I forgot to mention that one could use the netcdf-java package also to 
extract the data at a higher level.


http://www.unidata.ucar.edu/software/netcdf-java/

There's a interface to the package called ToolsUI which permits one to 
look at/display the data.

It's worth you time to inspect this package instead of dealing with the 
low level details of Grib unless you need too. There are netcdf-java Java 
Docs on the page too..


Robb...



On Fri, 24 Jul 2009, Chad Saxon wrote:

> Hi all,
> i recently have started to looking into reading grib1 and grib2 files using the 
> netcdf java library
> and need to extract the variables in the file along with their relative data. i 
> have some code here:
>
> public class GribPlugin {
>
> GribChecker file = new GribChecker();
> Grib1GridDefinitionSection gridSection;
>
>
> Grib1Input gribInput;
> Grib1ProductDefinitionSection productSection;
>
>
> Grib2ExtractRawData extract;
>
>
> ArrayList<String> gribRecords;
> ArrayList<String> gribProducts;
>
>
> String testfile = "Pacific.wind.grb";
> static int type;
>
>
> public GribPlugin() throws IOException, NoValidGribException, 
> NotSupportedException{
>
>
> ucar.unidata.io.RandomAccessFile gribfile = new 
> ucar.unidata.io.RandomAccessFile(testfile, "rw");
> type = file.getEdition(gribfile);
> System.out.println("File read in: " + testfile + ", Type of Grib File is " + 
> type);
>
>
> gribInput = new Grib1Input(gribfile);
>
>
> gribRecords = new ArrayList<String>();
> gribProducts = new ArrayList<String>();
>
>
> gribRecords = gribInput.getRecords();
> gribProducts = gribInput.getProducts();
>
>
> //extract = new Grib2ExtractRawData(gribfile);
> //gribRecords = extract.getRecords();
> //gribProducts = extract.getProducts();
>
>
> System.out.println("number of grib records: " + gribRecords.size());
> System.out.println("number of grib products: " + gribProducts.size());
>
>
> //System.out.println(gridSection.getNx() + " " + gridSection.getNy());
> //System.out.println("First lat coordinate: " + gridSection.getLa1() + " Last lat 
> coordinate: " +
> gridSection.getLa2());
> //System.out.println("First lon coordinate: " + gridSection.getLo1() + " Last lon 
> coordinate: " +
> gridSection.getLo2());
>
>
> }
>
> a printout of this code with this particular file yields:
>
> File read in: Pacific.wind.grb, Type of Grib File is 1
> number of grib records: 0
> number of grib products: 0
>
> I guess i don't know what i am looking for to get the data and am not as 
> familiar with this type of
> data as i should be. I guess i need to read up on what "records" or "products" 
> really are but i was
> wondering if there was any examples hidden somewhere in some javadoc from the 
> netcdf java website??
>
> thanks all for the help and suggestions!
>
> Chad

===============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
rkambic@xxxxxxxxxxxxxxxx                   WWW: http://www.unidata.ucar.edu/
===============================================================================