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Re: [h5md-user] units module
From: |
Pierre de Buyl |
Subject: |
Re: [h5md-user] units module |
Date: |
Wed, 16 Oct 2013 15:11:23 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Hi Konrad,
Thanks for your replies.
On Wed, Oct 16, 2013 at 08:35:54AM +0200, Konrad Hinsen wrote:
> Pierre de Buyl writes:
>
> > I just toyed a bit with udunits2 and it seems very nice. The fact that we
> can
> > rely on this software if need is good.
>
> Indeed. On the other hand, if we allow units to be as general as
> allowed by udunits, this means that every program wanting to read H5MD
> must either use udunits or re-implement a large subset of it.
Indeed, your restriction is fine.
> > In Mosaic [1], the restriction is, if I understand well:
> > 1. whitespace separation only (so no "." that is allowed with udunits).
> > 2. Not all units are allowed.
> > 3. No repeat units (no "m m", for instance, but only "m2").
> >
> > Konrad, can you confirm?
>
> Yes. My goal was to have something much simpler than udunits, given
> that Mosaic is meant for a much narrower application domain.
>
> > Also, I feel like I had to guess a few entries: c (speed of light?), Nav
> > (Avogadro's number?).
>
> All units have been documented in the Mosaic specification for a
> while, but I haven't yet put the HTML version on any public server. It
> will be on Github Pages, probably before the end of the week.
>
> BTW, you guessed right :-)
>
> > Is there some kind of "ultimate ASCII SI units definition" available? The
> xml
> > files from udunits2 seem close to that :-)
>
> It's the best collection I know of.
So, to get back to Peter's message:
I propose that we follow udunits grammar by restricting it similarly to Mosaic.
For reference, Mosaic's definition is
"""
The value of the units field is a text string in ASCII encoding. It contains a
sequence of unit factors separated by a space. A unit factor is a unit symbol
optionally followed by a non-zero integer which indicates the power to which
this factor is taken.
"""
I would remove the constants defined ("c" and "Nav"), however. We may want to
add "a unit string must be parseable by udunits"?
Cheers,
Pierre
- [h5md-user] units module, Peter Colberg, 2013/10/11
- Re: [h5md-user] units module, Pierre de Buyl, 2013/10/14
- Re: [h5md-user] units module, Konrad Hinsen, 2013/10/16
- Re: [h5md-user] units module,
Pierre de Buyl <=
- Re: [h5md-user] units module, Felix Höfling, 2013/10/16
- Re: [h5md-user] units module, Peter Colberg, 2013/10/16
- Re: [h5md-user] units module, Pierre de Buyl, 2013/10/17
- Re: [h5md-user] units module, Peter Colberg, 2013/10/17
- Re: [h5md-user] units module, Pierre de Buyl, 2013/10/17
- Re: [h5md-user] units module, Pierre de Buyl, 2013/10/17
- Re: [h5md-user] units module, Peter Colberg, 2013/10/17
- Re: [h5md-user] units module, Peter Colberg, 2013/10/17
- Re: [h5md-user] units module, Konrad Hinsen, 2013/10/19
- Re: [h5md-user] units module, Peter Colberg, 2013/10/19