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#95: Development of CF 1.5 Data Model -----------------------------+---------------------------------------------- Reporter: markh | Owner: [email protected] Type: task | Status: new Priority: medium | Milestone: Component: cf-conventions | Version: Resolution: | Keywords: -----------------------------+---------------------------------------------- Comment (by markh): Replying to [comment:41 mgschultz]: > Dear all, > > can't this issue be resolved simply by stating explicitly that the relation between the field and the domain axes depends on the software that is used to implement the data model? It seems that we all agree that there is and must be a "photo id". How this id is established (via a person at passport control or some automated scanner) is up to the implementation. > > Cheers, > > Martin Hello Martin I think you may well be right, that we need to agree at such a level of detail. I seem to be struggling to illustrate my concerns effectively. I think the domain_axis and coordinate model works very nicely for points arrays > length 1. All my concern is around coordiantes of length one and preserving the flexibility of interpretation of these. I work with a lot of data stored as 2D datasets which I aggregate based on metadata. How these datasets aggregate is interpreted by the metadata, the 'shape', 'ordering' etc emerges from the collection of 2D Fields. I want the ability to add a single valued coordiante to my Field without defining a domain_axis at any time. Additionally I want the ability to evaluate two or more Fields with single valued coordinates, establish that they share coordinate definitions and that the values are different. At this point I will create a new domain_axis on one Field, a new data dimension, and bind my new two-valued coordinate to this data dimension, aggregating my two Fields into one. By stating that the domain_axes are all defined by the Field, even if some of them are not evident as data dimensions, I feel I have lost this ability to see domain_axes emerge from my data as I aggregate. This has driven my suggestions to treat domain_axes not bound to data dimensions differently from bound domain_axes. May I have some assurance that the principal of what I am doing is consistent with interpretations of the design intent and that we are not mandating that 'all domain axes must be declared up front'? I do not think we should giving the impression of limiting the degrees of freedom of our Fields in this way. The [http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.6/cf- conventions.html#scalar-coordinate-variables flexibilty that CF NetCDF provides for size one coordiantes] is a really useful feature that I am worried we are desiging away in the model. Perhaps Martin's suggestion of a simpler, less prescriptive wording allows us to preserve this behaviour. mark -- Ticket URL: <https://cf-pcmdi.llnl.gov/trac/ticket/95#comment:42> CF Metadata <http://cf-pcmdi.llnl.gov/> CF Metadata This message came from the CF Trac system. To unsubscribe, without unsubscribing to the regular cf-metadata list, send a message to "[email protected]" with "unsubscribe cf-metadata" in the body of your message.
