Sorry to drag this out again, but I need to restate my question; it's
more or
less the opposite of the question that was answered.
Does the presence of a featureType attribute indicate that a file uses
the DSG
"machinery" and should therefore follow the guidelines of limited axes that
are spelled out in chapter 9?
Can I use this attribute and NOT have an instance (or station) dimension,
but stick with my current encoding:
float seatemp(time, depth, lat, lon)
rather than changing to:
float seatemp(station, time)
We need an attribute in oceansites files that indicates the type of
feature in the file -
multiple-depth moored instruments, single-depth moored instruments,
profiles ...
We'd like to use this attribute to fill that role, but if it is
overloaded in the sense that
it indicates something else about the file, we'll need to use another term.
Thanks -
Nan
On 8/29/13 9:55 AM, Jonathan Gregory wrote:
> Dear Nan
>
> It is allowed to use the new "machinery" of ch9 only if the featureType att
> is included. Perhaps we should put this in Appendix A - is that your
> suggestion? The new machinery is the incomplete multidimensional representation
> and the two ragged representations (which collapse the data variable into 1D)
> It is allowed to use the orthogonal rep (the data variable is samples*features)
> because that existed anyway, before ch9 was introduced, and there were already
> examples of it in the document.
>
> Best wishes
>
> Jonathan
>
> ----- Forwarded message from Nan Galbraith <ngalbraith at whoi.edu> -----
>
>> Date: Thu, 29 Aug 2013 09:46:14 -0400
>> From: Nan Galbraith <ngalbraith at whoi.edu>
>> User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:17.0)
>> Gecko/20130801 Thunderbird/17.0.8
>> To: cf-metadata at cgd.ucar.edu
>> Subject: [CF-metadata] featureType attribute (was CF-1.6 DSG clarification:
>> time series & lat/lon coordinates)
>>
>> Hi all -
>>
>> Quick question on the featureType attribute.
>>
>> Back in June, Jonathan Gregory said:
>>
>>> for a DSG (which is indicated by the presence of featureType)
>> I don't think this is stated clearly in the CF 1.6 manual, and as a
>> result, some
>> people have taken 'featureType' to be the equivalent of the 'cdm_data_type'
>> attribute.
>>
>> I'm not using discrete sampling geometries yet, and am not
>> completely familiar
>> with the details of this part of CF 1.6, but I understand that the
>> rules for allowed
>> coordinate variables (dimensions) are quite different from those of non-DSG
>> files.
>>
>> If the use of a single attribute changes the rules that much, I
>> think we need to
>> spell it out *very* clearly in the description of the featureType
>> attribute in the
>> CF document.
>>
>> Regards - Nan
>>
>>
>> On 6/5/13 9:08 AM, Jonathan Gregory wrote:
>>> Dear John
>>>
>>>> If we use the time series featureType as example
>>>>
>>>> (from http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.6/cf-conventions.html#idp8307552)
>>>>
>>>> AFAIU, the orthogonal multidimensional representation would be:
>>>>
>>>> float humidity(station,time)
>>>>
>>>> not
>>>>
>>>> float humidity(lat, lon, time)
>>> You are quite right, sorry. I was taking a step too far! The point is not only
>>> that the coordinates are size-1, but there is more than one of them. You are
>>> right that (lat,lon,time) can't be a timeseries discrete sampling geometry
>>> because it's got more than one spatial dimension. A timeseries DSG can have
>>> only one station (instance) dimension, and it is required to have both x and y
>>> coordinates. So these current rules mean that 2D field e.g. (lat,time) can't
>>> be a timeseries DSG.
>>>
>>> Like Mark, I saw the relevance of this to the discussion of scalar coordinates
>>> but I reached a different conclusion about it! At the moment, we are talking
>>> about the CF data model for version 1.5. DSGs were introduced in version 1.6.
>>> As a result of this discussion, it seems me that for a DSG (which is indicated
>>> by the presence of featureType), scalar coordinate variables have to be
>>> interpreted as auxiliary coordinate variables of an omitted size-one instance
>>> dimension. That is what is implied by section 9.2. It's different from the
>>> interpretation that is implied by section 5.7, which should exclude DSGs (and
>>> predates DSGs). I see no problem with having different interpretations for
>>> different purposes.
>>>
>>> Cheers
>>>
>>> Jonathan
>>>
Received on Tue Dec 03 2013 - 07:31:41 GMT
