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[netCDF #YGR-578319]: Question about NetCDF-4.0

Hi,

First, I think your English is excellent!  And we're glad you
were able to build netCDF-4.0.

> My question is : did you implement a way to convert an HDF5 files to
> NetCDF files, because in the bin/ directory after the installation I
> have just the ncdump and ncgen binaries. Do I have to use ncgen with a
> special way in order to make this convertion.

Although the ncdump included in netCDF-4.0 handles netCDF-4/HDF5 files,
the ncgen utility in netCDF-4.0 can only read the ncdump output for
files that use the netCDF classic data model of netCDF-3.  Hence that
ncgen program can only generate netCDF-3 classic files, or netCDF-4/HDF5
files that follow the classic model (by using the "-k 4' option).
A version of ncgen that handles the full netCDF-4 enhanced data model and
any output from ncdump is planned for the version 4.1 release of netCDF,
scheduled for the end of 2008.

However, there is a test version of the new ncgen, "ncgen4", that can
generate the C code needed to create a netCDF-4/HDF5 file.  It is
available in the current netCDF "snapshot release" from

  ftp://ftp.unidata.ucar.edu/pub/netcdf/snapshot/netcdf-4-daily.tar.gz

in the ncgen4 directory, and is built if you use the "--enable-ncgen4"
option to the configure script.  We accept bug reports for this test
relelase, but cannot promise support or quick bug fixes until the real
4.1 release.

If you want the ability to convert any HDF5 file to a netCDF-4 file, that
is only possible for files created through the netCDF-4 library, or files
that correspond to the netCDF-4 data model, a subset of the HDF5 data model.
The netCDF-4 data model is intentionally simpler than the full HDF5 data
model, and does not include such HDF5 features as:

  - non-hierarchical Group structures
  - HDF5 reference types
  - multiple links to a data object
  - user-defined atomic datatypes
  - stored property lists
  - attributes associated with user-defined types
  - szip compression
  - date/time type
  - object names that begin or end with a space
  - dimensions without associated dimension scales

I hope this answers your question.  Please let us know if you encounter
problems accessing or building the snapshot release.

--Russ


Russ Rew                                         UCAR Unidata Program
address@hidden                     http://www.unidata.ucar.edu



Ticket Details
===================
Ticket ID: YGR-578319
Department: Support netCDF
Priority: Normal
Status: Closed