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[CF-metadata] udunits handling of fuzzy time units

From: Christopher Barker <Chris.Barker>
Date: Tue, 15 Mar 2011 09:28:03 -0700

On 3/15/11 6:02 AM, John Caron wrote:
> so if currently we cant actually use months and years, because of the
> way udunits handles them,

I think udunits has nothing to do with it -- one shouldn't use months
and years in the context of "unit-of-time since a date", because it's
sloppy and ill-defined. Period, end of story.

There are various date-time libraries that will let you do math like:

a_date_time + 3 months.

But in that case, the actual length of "3 months" depends on the
date-time it is being added to.

On 3/15/11 9:13 AM, Steve Hankin wrote:

> Here I think concerns of human-readable formatting and convenience are
> sliding into issues of accurate encoding.

I agree -- human-readable formatting should be a very low concern for
this -- CF is about encoding data -- accuracy and clarity are far more
important.

> ncdump already offers an
> option to format these values as dates. Ncgen could in principle offer
> conversions to encode various human-friendly formatting options.

right -- human-readable is for utilities.

> This is one of those rare areas where our responsibility as
> software developers should be to push back against sloppy science, by
> offering software that makes it easy to do the calculations correctly,
> and help to end these sloppy practices.

Speaking as a scientist and a software developer -- hear hear!

And can we get rid of daylight saving time while we're at it? ;-)





-- 
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
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Received on Tue Mar 15 2011 - 10:28:03 GMT

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