I was unaware of this restriction on aux coordinate variables.
On 3/26/12 4:24 AM, Jonathan Gregory wrote:
> Appendix A notes that missing data is allowed in aux coord vars only in the
> case of discrete sampling geometries. This means the checker could regard it as
> an error also if it finds any missing data in aux coord vars, unless a valid
> featureType att is present, arising from 9.6, in addition to the above.
>
> However, I think the convention should be clear that this is not allowed except
> for discrete sampling geometries, so I'll open a defect ticket for that.
For something like towed CTD data, you might have a period of time where
data from the pressure sensor is missing. If neither the coordinate or aux
coordinate can contain null values, does this mean the only options are
interpolating Z or removing that section of data?
Sometimes, if the pressure can clearly be interpolated, we'd prefer to fill
the bad section with null Z values, and let the user decide if he would
like to
interpolate - otherwise the QC information can be lost when data is
extracted
from the file.
Cheers -
Nan
On 3/23/12 6:29 PM, John Caron wrote:
> On 3/23/2012 1:59 PM, Jim Biard wrote:
>> Hi.
>>
>> Jonathan's reply contained the section:
>>
>> 9.6 Where any auxiliary coordinate variable contains a missing
>> value, all
>> other coordinate, auxiliary coordinate and data values
>> corresponding to that
>> element should also contain missing values.
>>
>>
>> I thought I understood that missing values were forbidden for true
>> coordinate variables. Has this changed?
> No, coordinate variable cant have missing values but auxiliary
> coordinates can.
>
>> This requirement seems wrong to me anyway. If the values in the data
>> and auxiliary coordinate variables come from an external data source,
>> it is entirely possible that you could have a measurement missing
>> from one without it being missing from the other. Why force a
>> missing value into the data when you might, in fact, have a valid value?
>
>
> An auxiliary coordinate is important to have for valid data, not some
> optional information. If it is optional, dont make it an auxiliary
> coordinate.
>
> Allowing missing values in auxiliary coordinates is very useful, eg
> see the discrete sampling proposal, allowing you to use a rectangular
> array to store ragged arrays.
>
>
> John
>
>
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--
*******************************************************
* Nan Galbraith Information Systems Specailist *
* Upper Ocean Processes Group Mail Stop 29 *
* Woods Hole Oceanographic Institution *
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