Re: error saving empty matrix in HDF5 format

[Paul Kienzle]

On Mar 1, 2004, at 8:44 AM, David Bateman wrote:

> Ok there is a thread on this exact problem at
>
> http://www.unidata.ucar.edu/projects/coohl/mhonarc/MailArchives/ 
> netcdf-hdf-list/msg00097.html
>
> The bottom line is that, it appears that the HDF people are  
> implementing
> something like "H5Screate(H5S_EMPTY)" however that doesn't help us,  
> since
> the dimensionality of our empty matrices won't be maintained.... That  
> is
> a rank=n matrix when loaded will become "zeros(zeros(n))" and not the
> correct dimensionality.
>
> Frankly, I see no simple way to address this. The only thing I can see  
> is
> if we save an attribute in the HDF5 file flagging an empty matrix, then
> save the dimensions as a vector. This is slighly incompatibile in that
> if other software doesn't check this attribute then they'll end up
> loading a 1xN vector with the dimensions of the matrix instead of an
> empty matrix.....
>
> Should I go this way?

Can't you put the dimensions themselves in an attribute?  Other
applications could read the empty array and treat it as an empty
array, but octave aware applications could read the empty_dim
attribute and act accordingly.