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Leon, > On Fri, Feb 22, 2013 at 2:59 PM, Russ Rew <russ@xxxxxxxxxxxxxxxx> wrote: > > > > And I override these defaults by providing a chunksizes array when > > calling > > > NF90_DEF_VAR? > > > > Not quite. You have to call nc_def_var_chunking(..., chunkshape) for > > each variable *before* calling nc_enddef(). > > > I don't see a Fortran 90 equivalent of nc_def_var_chunking, and providing a > chunksizes array when calling NF90_DEF_VAR seems to have the desired > effect. For example: > > dimensions: > step = UNLIMITED ; > cell = 100 ; > variables: > float temperature(step, cell) ; > temperature:_Storage = "chunked" ; > temperature:_ChunkSizes = 1000, 100 ; > ... > > Am I missing something by doing it this way? Oops, sorry, I was answering in the context of the C API and should have noticed the question was about F90. There *is* a Fortran 90 equivalent to nc_def_var_chunking, using optional arguments to nf90_def_var: http://www.unidata.ucar.edu/netcdf/docs/netcdf-f90.html#NF90_005fDEF_005fVAR The "storage" and "chunksizes" arguments are what you want. Creating variable "special attributes" that begin with "_" won't work. The only special attribute that the library understands is "_FillValue". The other special attributes that begin with "_" were not intended for setting properties from library APIs, but just for displaying and setting them in CDL, as the ncgen documentation says: These special virtual attributes are not actually part of the file, they are merely a convenient way to set miscellaneous properties of the data in CDL The special attributes currently supported are as follows: `_Format', `_Fletcher32, `_ChunkSizes', `_Endianness', `_DeflateLevel', `_Shuffle', and `_Storage'. In recent versions of the C-based netCDF library, the ncgen utility interprets these special attributes and converts them into the necessary netCDF function calls, but the library functions don't do that. I guess we need to return an error for attempts to use special attributes in the library APIs as a substitute for function calls, if we're not going to interpret them at a low level in the library. --Russ
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