A Monday 25 May 2009 20:29:25 Eric Firing escrigué: > Francesc Alted wrote: > > A Monday 25 May 2009 19:55:28 Eric Firing escrigué: > >>>> If the aim is to come up with a method of saving numpy arrays that > >>>> uses a standard protocol and does not introduce large dependencies, > >>>> then could this be accomplished using netcdf instead of hdf5, > >>>> specifically Roberto De Almeida's pupynere, which is already in > >>>> scipy.io as netcdf.py? Or does hdf5 have essential characteristics > >>>> for this purpose that netcdf lacks? > > > > After looking a bit at the code of pupynere, there is the next line: > > > > assert magic == 'CDF', "Error: %s is not a valid NetCDF 3 file" % > > self.filename > > > > So, the current version of pupynere is definitely for version 3 of > > NetCDF, not version 4. > > Yes, and I presume it will stay that way--which is fine for the question > I am asking above. I should have said "netcdf3" explicitly. Its > simplicity compared to hdf5 and netcdf4 is potentially a virtue. > > The question is, is it *too* simple for the intended purpose?
I don't think the question is whether a format would be too simple or not, but rather about file compatibility. In that sense HDF5 is emerging as a standard de facto, and many tools are acquiring the capability to read/write this format (e.g. Matlab, IDL, Octave, Mathematica, R, NetCDF4-based apps and many others). Having this interchange capability is what should be seen as desirable, IMO. > > >>> >From what I understand, netCFD is based on on HDF5, at least as of the > >>> > >>> version 4 release. > >> > >> Netcdf4 is indeed built on hdf5, but netcdf3 is not, and netcdf3 format > >> is likely to stick around for a *very* long time. The netcdf4 library > >> is backwards-compatible with netcdf3. > > > > NetCDF4 is backwards-compatible with NetCDF3 just at API level, not the > > file format. NetCDF3 has a much more simple format, and completely > > different from NetCDF4, which is based on HDF5. > > Yes, but the netcdf4 *library* includes full netcdf3 compatibility; you > can read and write netcdf3 using the netcdf4 library. For example, you > can build Jeff Whitaker's http://code.google.com/p/netcdf4-python/ with > all the hdf5 bells and whistles, and it will still happily read and, > upon request, write netcdf3 files. Again, I think that the issue is compatibility with other tools, not just between NetCDF3/NetCDF4 worlds. -- Francesc Alted _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
