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Incosistent definition of aggregate dimension in MFDataset documentation #167

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
The documentation of MFDataset seems to give a contradictory definition of 
aggregate dimension.

From 
http://netcdf4-python.googlecode.com/svn/trunk/docs/netCDF4.MFDataset-class.html
:
  Open a Dataset spanning multiple files, making it look as if it was a single file.
  Variables in the list of files that share the same dimension (specified with the keyword aggdim) are aggregated.
  If aggdim is not specified, the unlimited is aggregated.
  Currently, aggdim must be the leftmost (fastest varying) dimension of each of the variables to be aggregated.

The documentation says that the aggregate dimension is the leftmost one, and 
adds the hint 'fastest varying'. The leftmost variable is the slowest varying. 
This is also consistent with aggregating over the record dimension, as 
described in described in NetCDF documentation.
From http://www.unidata.ucar.edu/software/netcdf/docs/netcdf/Dimensions.html:
  A netCDF classic or 64-bit offset dataset can have at most one unlimited dimension, but need not have any.
  If a variable has an unlimited dimension, that dimension must be the most significant (slowest changing) one.
  Thus any unlimited dimension must be the first dimension in a CDL shape and the first dimension in corresponding C array declarations.

Original issue reported on code.google.com by jbelt...@socib.es on 4 Mar 2013 at 1:25

GoogleCodeExporter commented 9 years ago 
Agreed.  Changed the wording to "slowest varying dimension" in the docstring.  
Surprised no one (including me) noticed that before ...

Original comment by whitaker.jeffrey@gmail.com on 4 Mar 2013 at 1:41