[SciPy-user] HDF5 vs FITS (was: Fast saving/loading of huge matrices)

Perry Greenfield perry@stsci....
Sun Apr 22 09:23:48 CDT 2007

On Apr 22, 2007, at 6:02 AM, Francesc Altet wrote:

> Hi Perry,
> El dv 20 de 04 del 2007 a les 17:14 -0400, en/na Perry Greenfield va
> escriure:
>> I think that is a bit too broadly posed to answer in any simple way
>> (if you are wondering how HDF and FITS compare). Speed? Flexibility?
>> Etc. FITS is generally much less flexible. However, it is archival.
>> Something that HDF has a harder time claiming. And it is very well
>> entrenched in astronomy.
> Sorry for my ignorance, but can you explain what 'archival' term means
> in this context?  I suppose that it has a very concrete meaning, but I
> can't realize why a flexible format like HDF5 is not appropriate for
> archival (in the general sense of the term) purposes.
What I meant was that FITS was defined in terms of the actual binary  
representation (originally on tape, but now generalized to other  
storage). The idea being that once written as a FITS file, it would  
always be supported in the future as a format. With HDF, the focus  
(as I understood it) was on the software interface, and that the  
binary representation used may change. And for HDF that binary  
representation has changed over time (again, as I understand it,  
perhaps I've been misinformed). That kind of variability is a real  
killer for archival purposes. Is HDF5 considered stable enough that  
no future changes are envisioned? (And have they guaranteed to  
support HDF5 indefinitely even if new enhancements are proposed?).  
That's what it would take to be accepted as an archival format.


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