[CF-metadata] Dealing with large numbers of flag values innetcdf cf

From: John Caron <caron>
Date: Tue, 27 Oct 2009 07:08:25 -0600

martin.juckes at stfc.ac.uk wrote:
> Thanks for the responses.
>
> Seth is right, I was looking for an alternative to having a gigantic "flag_meanings" attribute.
>
> I have tried Seth's approach, but can?t get it past the cf-checker. There appears to be a character set restriction: I can get the first 547 flag_meaning strings accepted if I remove all the "-", "." and "," characters. I'm reasonably sure there are no control characters in the following strings which could be responsible for the error message that I get (ERROR (3.5): Invalid syntax for 'flag_meanings' attribute) when I increase the number of flag_meanings to 550. Could it be something to do with the string length (16472 characters)?

That seems to be an error in the cf-checker (?) I think attribute values should be any UTF-8 encoded Unicode characters (aka UTF-8 string).


>
> I could try abbreviating the flag_meanings, but this would either be tedious work by hand or liable to create confusion if done automatically. If you could point me to some information about exactly what string format is acceptable, that would be very helpful.
>
> To answer John's question: I'm currently using netcdf 3, in IDL -- I'm not sure what the options for upgrading to netcdf 4 are.

I mention netcdf-4 because it has enum types - which would be a nice solution for this class of problems, at least when you want to include the meanings of the flags in the file.
Received on Tue Oct 27 2009 - 07:08:25 GMT