Hello Jim, Julien,
I'm not sure .. I think the conformance might be right here and your flag_values should be 0,1,2,3, 4, 8,12,16, and flag_masks 3,3,3,3,28,28,28,28 If, for instance, you very_bad_quality and very_bad_weather, then "var" should have value 4 = '00100000` in binary. Masked with 3 (11000000) gives zero, and masked with 28 (00111000) gives 4. Re-using the zero value would make zero ambiguous, so you need to start the 2nd sequence at 4. regards, Martin ________________________________ From: CF-metadata <[email protected]> on behalf of Jim Biard <[email protected]> Sent: 20 November 2018 16:51:24 To: [email protected] Subject: Re: [CF-metadata] Multiple zeros in flag_values allowed? Julien, That's fine. The conformance document probably needs a better statement of the requirement when flag masks are used. Grace and peace, Jim On 11/20/18 11:40 AM, Julien Demaria wrote: Hi, We want to define a flags variable defining like that: var:flag_masks = 3, 3, 3, 3, 12, 12, 12, 12 ; var:flag_values = 0, 1, 2, 3, 0, 4, 8, 12 ; var:flag_meanings = “very_bad_quality bad_quality good_quality very_good_quality very_bad_weather bad_weather good_weather very_good_weather” ; I understand from http://cfconventions.org/Conformance/conformance.html that it is not allowed to use several time the same value (here zero) in flag_values: Requirements: · The flag_values attribute values must be mutually exclusive among the set of flag_values attribute values defined for that variable. So it means that for each new “bits combination” in the flags definition we lost one of the combination because we cannot use zero more than one time? Do you confirm this? What is the reason? Thanks in advance, Julien _______________________________________________ CF-metadata mailing list [email protected]<mailto:[email protected]> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -- [CICS-NC] <http://www.cicsnc.org/> Visit us on Facebook <http://www.facebook.com/cicsnc> Jim Biard Research Scholar Cooperative Institute for Climate and Satellites NC <http://cicsnc.org/> North Carolina State University <http://ncsu.edu/> NOAA National Centers for Environmental Information <http://ncdc.noaa.gov/> formerly NOAA’s National Climatic Data Center 151 Patton Ave, Asheville, NC 28801 e: [email protected]<mailto:[email protected]> o: +1 828 271 4900 Connect with us on Facebook for climate<https://www.facebook.com/NOAANCEIclimate> and ocean and geophysics<https://www.facebook.com/NOAANCEIoceangeo> information, and follow us on Twitter at @NOAANCEIclimate<https://twitter.com/NOAANCEIclimate> and @NOAANCEIocngeo<https://twitter.com/NOAANCEIocngeo>. _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
