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

• To: Jeff Whitaker <jswhit@xxxxxxxxxxx>
• Subject: Re: [netcdfgroup] Ann: NCL/PyNIO now have support for netCDF-4 classic format
• From: Ed Hartnett <ed@xxxxxxxxxxxxxxxx>
• Date: Mon, 27 Aug 2007 10:38:17 -0600

Jeff Whitaker <jswhit@xxxxxxxxxxx> writes:

> 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
>

Howdy Mary and Jeff!

Just wanted to point out that compression is a per-variable feature,
not a per-file feature.

That is, different variables in the file can have different
compression factors (or none at all).

Thanks!

Ed

-- 
Ed Hartnett  -- ed@xxxxxxxxxxxxxxxx

• References:
  • [netcdfgroup] Ann: NCL/PyNIO now have support for netCDF-4 classic format
    • From: Mary Haley
  • Re: [netcdfgroup] Ann: NCL/PyNIO now have support for netCDF-4 classic format
    • From: Jeff Whitaker