[netCDFJava #CQJ-124352]: Writing netCDF file using netCDF Java 4.1

> John,
> 
> Thanks for the info.  I suspected that groups weren't implemented based
> on the resulting file.  I've implemented my data model using all global
> variables and attributes, which will work, but it's very messy.  I have
> 40+ channels of data which each have their own attributes, so I end up
> with a huge list of variables and attributes.
> 
> I'm trying to avoid using the C library interface since I'm trying to
> minimize platform dependencies.
> 
> I'm very happy to be able to read hdf files directly in Java and output
> the simple netcdf format for my data model.  I'm curious about the
> future development and enhancement of the Java library.  I hope that it
> will continue be be developed since I would like to base several data
> readers on it.  

The netCDF-Java library is an integral part of Unidata's development plans, so 
it will continue to be developed and enhanced into the forseeable future.

> I have already written a MODIS reader (ported from a C
> program) using the Java API, and I'm thining about porting a McIdas, and
> ASTER (hdf) reader also.

I would be very interested in incorporating your code into the base, if 
possible.

> 
> FYI, Here is the project I'm working on.  You can add it to your list of
> packages using the Java netCDF library.
> 
> http://miningsolutions.itsc.uah.edu/glider/

very cool, i will add.

> 
> Thanks,
> Todd
> 
> Unidata netCDF Java Support wrote:
> > Hi Todd:
> >
> > Netcdf-Java can only write to netcdf-3 format, which does not support 
> > groups. I realize the API is confusing, since NetcdfFileWriteable 
> > subclasses NetcdfFile which has an addGroup() method. I will refactor 
> > eventually to clarify that.
> >
> > Meanwhile, the only way to use Groups is in netcdf-4, which requires the C 
> > library. We may eventually have a JNI interface to it, but not yet.
> >
> > John
> >
> >
> >> Hi,
> >>
> >> I'm trying to create a netCDF file using the netCDF Java 4.1 and I'm
> >> having some trouble.  I'm trying to use groups, but I haven't found a
> >> good example with the current API.  So my first question is are groups
> >> even supported in the output API?  I'm able to create an output file,
> >> but the groups seem to be ignored.  Instead, the variables in shown in
> >> the NetCDFTools app as group/varname, but no groups are defined.  In my
> >> program, the NetcdfFile.findGroup method also fails to find the groups
> >> when I try to read in the created file.
> >>
> >> Here's a snippet of the code that creates the group and it's attributes
> >> and variables
> >>
> >> // previous open in another method
> >> NetcdfFileWriteable fptr =
> >> NetcdfFileWriteable.createNew(GliderFilename, false);
> >>
> >> Group g=new Group(fptr, null, mGroupName);
> >> fptr.addGroup(null, g);
> >>
> >> // dimensions are defined global
> >> fptr.addVariable(g,"Image", DataType.SHORT, "NumberOfLines
> >> NumberOfPixels");
> >>
> >> fptr.addAttribute(g, new Attribute("Key", new Integer(mKey)));
> >> fptr.addAttribute(g, new Attribute("Type", new Integer(mType)));
> >> fptr.addAttribute(g, new Attribute("Units", new Integer(mUnits)));
> >> fptr.addAttribute(g, new Attribute("NumPix", new Integer(mNumPix)));
> >> fptr.addAttribute(g, new Attribute("NumLines", new
> >> Integer(mNumLines)));
> >> fptr.addAttribute(g, new Attribute("ChannelWaveLength", new
> >> Float(mChannelWaveLength)));
> >> fptr.addAttribute(g, new Attribute("SpatialResolutionX", new
> >> Float(mSpatialResolutionX)));
> >> fptr.addAttribute(g, new Attribute("SpatialResolutionY", new
> >> Float(mSpatialResolutionY)));
> >> fptr.addAttribute(g, new Attribute("DataByteSize", new
> >> Integer(mDataByteSize)));
> >> fptr.addAttribute(g, new Attribute("MaxValue", new
> >> Float(mMaxValue)));
> >> fptr.addAttribute(g, new Attribute("MinValue", new
> >> Float(mMinValue)));
> >> fptr.addAttribute(g, new Attribute("ChannelLabel", new
> >> String(mChannelLabel)));
> >> fptr.addAttribute(g, new Attribute("ChannelComment", new
> >> String(mChannelComment)));
> >>
> >> // set up channel LUT for scaling one and two byte unsigned values
> >> if (mChannelLUT!=null) {
> >> Array lut = Array.factory( mChannelLUT);
> >> fptr.addAttribute(g, new Attribute("ChannelLUT", lut));
> >>
> >> }
> >>
> >> fptr.addVariable(g,"HistogramMaxValue", DataType.FLOAT,null);
> >> fptr.addVariable(g,"HistogramMinValue", DataType.FLOAT,null);
> >> fptr.addVariable(g,"HistogramBins", DataType.INT,
> >> "NumHistogramBins");
> >>
> >> It seems like all of these things get interpreted as global and the
> >> group is ignored.  Am I missing something?
> >>
> >> Thanks,
> >>
> >> Todd
> >>
> >>
> >>
> >>
> >
> >
> > Ticket Details
> > ===================
> > Ticket ID: CQJ-124352
> > Department: Support netCDF Java
> > Priority: Normal
> > Status: Closed
> >
> >
> >
> 
> 
> --
> __________________________________________
> 
> Todd Berendes
> Research Scientist
> Information Technology and Systems Center
> University of Alabama in Huntsville
> (256) 824-4251
> address@hidden
> __________________________________________
> 
> 


Ticket Details
===================
Ticket ID: CQJ-124352
Department: Support netCDF Java
Priority: Normal
Status: Open