It's been some time since we have worked on this, but my recollection is
that HDF 5 was moving rapidly at the time and we decided to implement HDF 5
and netCDF 4 files at a certain point in time rather than try to
incorporate everything that was happening in HDF 5. In theory this means
that files written by Nujan should be readable by HDF 1.8.5 and later and
the C NetCDF API 4.1.1 or later. Nujan does not currently support updating
files, only creating new ones. One feature I know is unsupported is header
compression, which for small files can be more significant.
I can't speak to the API similarities as I haven't used both APIs.
However, you can start with NhFileWriter
<https://github.com/NCAR/nujan/blob/master/src/main/java/edu/ucar/ral/nujan/netcdf/NhFileWriter.java>
.
I just fixed the POM dependencies so it is buildable by others now. Fixes
and improvements welcome.
Aaron
On Fri, Jun 30, 2017 at 11:41 AM, Hanns Holger Rutz <rutz@xxxxxx> wrote:
> hello aaron,
>
> thanks for this project link, I will check it out. I guess the API is
> not identical, though? Can I use `ma2.Array` and things like that?
>
> best, .h.h.
>
>
> On 30/06/17 19:36, Aaron Braeckel wrote:
> > Hello,
> >
> > a pure-Java library exists for writing netCDF 4 and HDF
> > 5: https://github.com/NCAR/nujan. We've not put much time into this
> > recently and the JNI/native alternative will have a lot more options and
> > features, but Nujan may be another option for you to consider.
> >
> > Aaron
> >
> > On Fri, Jun 30, 2017 at 11:29 AM, Hanns Holger Rutz <rutz@xxxxxx
> > <mailto:rutz@xxxxxx>> wrote:
> >
> > I see -- and it's not possible to draw them in as standard Maven
> > dependencies for the correct platforms? I think this works with other
> > Java-C-bridging libraries such as OpenCV, for example:
> >
> > http://search.maven.org/#search%7Cga%7C1%7Copencv
> > <http://search.maven.org/#search%7Cga%7C1%7Copencv>
> >
> > you have there linux-armhf.jar, linux-x86.jar, linux-x86_64.jar,
> > macosx-x86_64.jar, windows-x86.jar etc.
> >
> > would it be possible to do that with NetCDF as well?
> >
> > best, .h.h.
> >
> >
> > On 30/06/17 19:10, Sean Arms wrote:
> > > Greetings!
> > >
> > > Currently, the only way to write netCDF-4 files is through the C
> > interface:
> > >
> > >
> > https://www.unidata.ucar.edu/software/thredds/current/
> netcdf-java/reference/netcdf4Clibrary.html
> > <https://www.unidata.ucar.edu/software/thredds/current/
> netcdf-java/reference/netcdf4Clibrary.html>
> > >
> > > As it stands, there isn't a pure implementation of HDF5 outside of
> the
> > > C library, so pretty much everyone who writes netCDF needs to go
> > > through the C library.
> > >
> > > Sean
> > >
> > >
> > > On Fri, Jun 30, 2017 at 9:55 AM, Hanns Holger Rutz <rutz@xxxxxx
> > <mailto:rutz@xxxxxx>> wrote:
> > >> p.s. I use
> > >>
> > >> "edu.ucar" % "netcdf4" % "4.6.10"
> > >>
> > >> as library. perhaps I need to change this or use a different one?
> > >>
> > >>
> > >> On 30/06/17 17:51, Hanns Holger Rutz wrote:
> > >>> hi,
> > >>>
> > >>> so far I have used this
> > >>>
> > >>> nc2.NetcdfFileWriter.createNew(Version.netcdf3, location,
> null)
> > >>>
> > >>> this creates files with this type of header:
> > >>>
> > >>> 00000000 43 44 46 01 00 00 00 00 00 00 00 0a 00 00 00 04
> > >>> |CDF.............|
> > >>> 00000010 00 00 00 04 54 69 6d 65 00 00 00 b4 00 00 00 09
> > >>> |....Time........|
> > >>> 00000020 4c 6f 6e 67 69 74 75 64 65 00 00 00 00 00 00 0c
> > >>> |Longitude.......|
> > >>> 00000030 00 00 00 08 4c 61 74 69 74 75 64 65 00 00 00 24
> > >>> |....Latitude...$|
> > >>> 00000040
> > >>>
> > >>> now I have a problem where I have to include 64-bit long values,
> and
> > >>> this seems to be unsupported: "long not support in netcdf-3"
> > >>>
> > >>> So I tried chaing this to
> > >>>
> > >>> nc2.NetcdfFileWriter.createNew(Version.netcdf4, location,
> null)
> > >>>
> > >>> now this gives me error that it wants to use C (???) libraries:
> > >>>
> > >>> Nc4Iosp: NetCDF-4 C library not present
> > (jna_path='/usr/local/lib/',
> > >>> libname='netcdf').
> > >>>
> > >>> What should I do? I need a solution that is cross-platform with
> > >>> libraries pulled from a maven repository, no matter whether user
> > runs
> > >>> Linux, Windows, Mac.
> > >>>
> > >>> Can I get a pure Java solution that supports 64-bit long? How?
> > >>>
> > >>> thanks, .h.h.
> > >>>
> > >>>
> > >>>
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