John,
As we are feeling our way along here, I think we felt that we needed to
have a single coordinate variable that we could hang attributes on that
would make it clear that the associated dimension was enumerating
different bands. Thus the "bandit" coordinate variable in my example
that had an axis type of "index" and a standard_name of "band". If we
dropped this coordinate variable altogether, the netCDF would still be
proper, but where/how would we make it clear (to a general-purpose,
CF-aware application) what the "bandit" dimension is for?
I guess a valid question to ask is - do we need such an indicator? Or
put another way, what would be a good (or, the best) way to provide
signposts for an application that is trying to recognize the type of
data and do something smart with it? I am sure I don't know.
Grace and peace,
Jim
On 7/26/2011 2:51 PM, John Caron wrote:
On 7/25/2011 1:00 PM, Tom Whittaker wrote:
John:
On Mon, Jul 25, 2011 at 9:51 AM, John Caron<caron@xxxxxxxxxxxxxxxx>
wrote:
Another way to say the same thing: A coordinate variable must have
values
that are a "sampling" along a continuous domain. One sees this
violated in
the poorly designed AWIPS netcdf files, eg where all "temperature"
values
are crammed into one variable, and the coordinate values have both
pressure
and height and potential temperature, etc.
Is it possible (practical) to define a simple "index" as a coordinate
variable? What I'm thinking here is that we could define some
coordinate axis types like "wavelength", etc., but would also need
something that is just a simple index with a well-known attribute that
could be easily recognized. In this "simple index" case, the data
provider would have to supply other variables, dimensioned by "band"
(for example) that would further describe the meaning of these
indecies (for example: wavelength(band) would contain the central
wavelength value).
If this reasonable, then I could see us creating a few new coordinate
axis names ("wavelength", "wavenumber") along with this simple index
(name to be determined), and then start defining some standard_names
for the ancillary metadata as well.
tom
Im not sure what the point of an "index coordinate" where coord(i) =
i. is it just to have a container variable for where the other
coordinates are referenced?
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Jim Biard
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