[netcdfgroup] Ann: NCL/PyNIO now have support for netCDF-4 classic format

[Jeff Whitaker]

David Brown wrote:
> Hi Jeff,
>
> Currently NCL and PyNIO turn on the shuffle filter whenever  
> compression is requested.
> My reading of the docs suggested that there were no disadvantages to  
> having shuffle set on all
> the time, and so I did not make it an option in the interest of  
> keeping things simple.
>
> So is this okay as far as you (or anyone else with knowledge of these  
> things) are concerned,
> or do I need to make this something the user controls? It would be  
> easy enough to make it optional,
>   -dave
>
>
>   
Dave:  That sounds fine to me. 

-Jeff
> On Aug 27, 2007, at 9:39 AM, Jeff Whitaker wrote:
>
>   
>> Mary Haley wrote:
>>     
>>> Hi all,
>>>
>>> This is a bit of a late announcement, but NCL V4.3.1 and PyNIO V1.2.0
>>> have support built-in for reading and writing netCDF-4 classic files
>>> on systems where netcdf-4.0-beta1 is supported.
>>>
>>> With NCL, you can write a netCDF-4 classic file by calling the
>>> "setfileoption" procedure with the "format" option before you call
>>> "addfile" to create a netCDF-4 classic 4 file:
>>>
>>>    setfileoption("nc","format","netcdf4classic")
>>>    a = addfile("file.nc","c")
>>>
>>> You can further specify a compression level:
>>>
>>>    setfileoption("nc","compressionlevel",5)
>>>
>>> Similar code exists for PyNIO:
>>>
>>> import Nio
>>> opt                  = Nio.options()
>>> opt.Format           = "netcdf4classic"
>>> opt.CompressionLevel = 5
>>>
>>> fout = Nio.open_file("file.nc","c",opt)
>>>
>>> For more information, see the NCL "setfileoption" or PyNIO  
>>> documentation:
>>>
>>>    http://www.ncl.ucar.edu/Document/Functions/Built-in/ 
>>> setfileoption.shtml
>>>    http://www.pyngl.ucar.edu/Nio.shtml
>>>
>>> For download:
>>>
>>>     http://www.ncl.ucar.edu/Download/
>>>     http://www.pyngl.ucar.edu/download.shtml
>>>
>>> Cheers,
>>>
>>> --Mary
>>>
>>>
>>>       
>> Mary:  Can you turn the shuffle filter on with setfileoption?  I've  
>> found that it can really improve the compression ratios when used  
>> in conjunction with zlib compression in netcdf-4 files.
>>
>> -Jeff
>>
>> -- 
>> Jeffrey S. Whitaker         Phone  : (303)497-6313
>> Meteorologist               FAX    : (303)497-6449
>> NOAA/OAR/PSD  R/PSD1        Email  : Jeffrey.S.Whitaker at noaa.gov
>> 325 Broadway                Office : Skaggs Research Cntr 1D-124
>> Boulder, CO, USA 80303-3328 Web    : http://tinyurl.com/5telg
>>
>>     
>
>
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-- 
Jeffrey S. Whitaker         Phone  : (303)497-6313
Meteorologist               FAX    : (303)497-6449
NOAA/OAR/PSD  R/PSD1        Email  : Jeffrey.S.Whitaker at noaa.gov
325 Broadway                Office : Skaggs Research Cntr 1D-124
Boulder, CO, USA 80303-3328 Web    : http://tinyurl.com/5telg