Hello David,
I just noticed a typo in my email that might of confused some of you: I
meant to say "*shouldn't* conflict between variables you want to
aggregate" (otherwise it probably wouldn't make sense to aggregate them).
Perhaps you should treat the standard CF global attributes like the
non-standard ones and include only those that are identical across
aggregated variables.
best,
Karl
On 3/19/12 1:16 PM, David Hassell wrote:
Hello Karl,
An astute point. I confess to sweeping this under the carpet a little
bit and ignoring (deleting) the standard CF global attributes as given
in appendix A, but insisting that non-standard ones are identical for
aggregated fields.
This is an easy and pragmatic approach as a programmer, but probably
not the most useful one? For me, it raises issues such as whether or
not an attribute should be a scalar auxiliary coordinate, or could
perhaps be 'promoted' to be one during the aggregation. Or perhaps
such attributes should be concatenated? etc. This area is
deliberately not regulated in our CF aggregation rules - rather
leaving it to an implementation's, or the users, discretion, which can
vary with application.
Since a tool should be useful to the users (not just easy for
programmers!), opinions are welcome.
All the best,
David
---- Original message from Karl Taylor (10AM 19 Mar 12)
Date: Mon, 19 Mar 2012 10:51:36 -0700
From: Karl Taylor<[email protected]>
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5; rv:10.0.2)
Gecko/20120216 Thunderbird/10.0.2
To: [email protected]
Subject: Re: [CF-metadata] cf2cf - a new tool
presumably this tool is limited to combining files with identical
global attributes? Of course the global attributes should conflict
between variables that you want to aggregate.
Karl
On 3/19/12 10:28 AM, David Hassell wrote:
Hello,
I'd like to advertise a hopefully useful new tool called 'cf2cf' for
combining many CF-netCDF files into a single CF-netCDF file, where the
input fields are aggregated into as few multidimensional netCDF
variables as possible.
This is a command line utility which utilizes the proposed CF
aggregation rules (trac ticket #78) to combine CF fields based on
their metadata. In particular differing variables' units, dimension
order, dimension direction and netCDF variable names are are accounted
for in the aggregation process.
A quick, simple example:
% cf2cf -o one_output_file.nc lots_of_input_files*.nc
All details, including full documentation, more examples and
installation, may be found at
http://www.met.reading.ac.uk/~david/cf2cf.html
This tool uses the python cf package
(http://code.google.com/p/cf-python), which also makes the same CF
aggregation and the CF data model (trac ticket #68) available in an
API, in a memory efficient manner.
Any feedback, positive or negative, on cf2cf, the CF aggregation rules
and the cf python package would, of course, be most gratefully
received, to help make these better.
All the best,
David
--
David Hassell
National Centre for Atmospheric Science (NCAS)
Department of Meteorology, University of Reading,
Earley Gate, PO Box 243,
Reading RG6 6BB, U.K.
Tel : 0118 3785613
Fax : 0118 3788316
E-mail: [email protected]
_______________________________________________
CF-metadata mailing list
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http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
_______________________________________________
CF-metadata mailing list
[email protected]
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
--
David Hassell
National Centre for Atmospheric Science (NCAS)
Department of Meteorology, University of Reading,
Earley Gate, PO Box 243,
Reading RG6 6BB, U.K.
Tel : 0118 3785613
Fax : 0118 3788316
E-mail: [email protected]
_______________________________________________
CF-metadata mailing list
[email protected]
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
