Re: [h5md-user] Varying particle number

[pdebuyl]

On Tue, Oct 07, 2014 at 12:02:37AM -0400, Peter Colberg wrote:
> For the case of varying particle number, I propose a data element
> “particles/<subgroup>/particle_number” that contains the number
> of particles at a given step. An “id” data element may or may not
> be present. When “particle_number” is present and “id” is absent,
> the particle data shall be contiguous, i.e., without holes.
> 
> The background is that I would like to store a varying subset of
> indistinguishable solvent particles (~10³ of a total of 10⁶) and
> efficiently retrieve the particle data for visualization.

Before going further with "particle_number", did you test your situation with a
compressed "id" element?

Alternatively, a better compression could be achieved if we decided to allow
"species" to contain also a fill value. This way, you'd compress a dataset of
fill_value, 0, 1 (for two species, for instance) and that should be more
efficient. 

P