Re: zero length attrributes...

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Is a zero-length attribute in netCDF the same as a scalar, or is it more like an empty array? I can't imagine a use for the latter, but if it's needed it's needed.


At 12:45 PM 11/10/2003, Ed Hartnett wrote:
Howdy all!

The topic of the day is the perhaps mythical zero length attribute.

Why would one want a zero length attribute? I will leave that question
for the philosophers among us.

Does anyone really use zero-length attributes in the netcdf universe?
Probably there is someone out there who does, since there are a large
number of users out there.

Meanwhile, netcdf supports a zero length attribute, but HDF5,
apparently, does not. When I try to create one I get:

HDF5-DIAG: Error detected in HDF5 library version: 1.6.1 thread 0. Back trace follows. #000: H5S.c line 1708 in H5Screate_simple(): zero sized dimension for non-unlimited dimension
    major(01): Function arguments
    minor(05): Bad value

Woops! So that doesn't work. My reading of the manual on H5Acreate
informs me that:

 Currently only simple dataspaces are allowed for attribute dataspaces.

So I can't use an extensible attribute.

What do you think, Quincey, is there a way to have a zero length
attribute in HDF5?



Mike Folk, Scientific Data Tech (HDF)
NCSA/U of Illinois at Urbana-Champaign          217-244-0647 voice
605 E. Springfield Ave., Champaign IL 61820 217-244-1987 fax

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