Re: HDF5 dimension scales proposal




Robert E. McGrath wrote:

As the document makes clear, the proposal is definitely on the 'light weight'
side, leaving the most complex stuff to applications.

1. A dimension scale will be a dataset, and wont be hidden, so wont it always appear in a group and have a name there?


Yes. This is the design.

So, then should the name beconsidered  optional?

"Since some applications do not wish to apply names to dimension scales, we recommended that dimension scale names be optional."




4. I think the main place where your proposal may fail to cover the general case is that you seem to require that a dimension scale is associated with a single dimension. But the general case is that it can be associated with several dimensions, eg lat(x,y). For that case, it makes more sense to associate a dimension scale with a dataspace. But then you still have to associate the dimensions of the data dataset with the dimensions of the dimension scale dataset. Giving the dimensions names and requiring their lengths to be the same would work, and would be an implementation of shared dimensions for the case of shared dimension scales.


This is not provided in the proposed design.  Applications must implement
this semantics through their own conventions, I think.

It seems like you are missing a very important use case, namely lat(x,y), lon(x,y), where "lat" and "lon" are dimension scales that are each associated with the two shared dimensions "x" and "y". How would you propose to handle this in HDF5 with dimension scales?