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I don't know what to say. I think there are several groups reading and writing variable length arrays. I hope this doesn't prevent me/others from reading existing files or change the way their files are written since collections would then be a mix. On Sunday, November 6, 2016, dmh@xxxxxxxx <dmh@xxxxxxxx> wrote: > Clarification 1: > > I was probably too terse in my previous message about variable-length > dimensions. Let me elaborate a bit. > > All existing dimensions (including UNLIMITED) have > (at any point in time) a fixed known size and every use of that dimension > has that size. Note that an UNLIMITED dimension's size may change over > time, but it is still the case that all occurrences of it have the same > size at any point in time. > > A variable-length dimension (often represented by "*") has potentially > a different size for every occurrence at any given point in time. > The pretense that a variable-length dimension is a dimension causes > significant code and use complications in the CDM data model. > > An ArraySequence is particular form of CDM Array, similar to an > Array Structure, that encapsulates the fact the the length of the sequence > can differ for each ArraySequence instance. The goal of the proposed change > is to isolate/encapsulate true variable-length objects within an > ArraySequence object. > > So, if we have, for example, > int x(5,*) > then this would be represented as a 5 element array of > ArraySequence objects, and each ArraySequence object > contains a variable length vector of integers. > Using the netcdf-4 model, this would be: > types: int(*) sequence_t > variables: sequence_t x(5) > > The requirement on e.g. IOSP developers is that they create ArraySequence > objects, and the requirement on the client users of CDM (via the > netcdf-Java library) is that they recognize ArraySequence objects. > > My speculation is that anyone who uses variable-length dimensions already > has to make code exceptions to process it, and it is probable that only > that code would need to be changed to deal with ArraySequence. > > Note: ArraySequences actually already exist in the CDM code, but are > currently not used (AFAIK). > > =Dennis Heimbigner > Unidata > > _______________________________________________ > NOTE: All exchanges posted to Unidata maintained email lists are > recorded in the Unidata inquiry tracking system and made publicly > available through the web. Users who post to any of the lists we > maintain are reminded to remove any personal information that they > do not want to be made public. > > > netcdf-java mailing list > netcdf-java@xxxxxxxxxxxxxxxx > For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ -- Sincerely, Bob Simons IT Specialist Environmental Research Division NOAA Southwest Fisheries Science Center 99 Pacific St., Suite 255A (New!) Monterey, CA 93940 (New!) Phone: (831)333-9878 (New!) Fax: (831)648-8440 Email: bob.simons@xxxxxxxx The contents of this message are mine personally and do not necessarily reflect any position of the Government or the National Oceanic and Atmospheric Administration. <>< <>< <>< <>< <>< <>< <>< <>< <><
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