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

  • To: Mary Haley <haley@xxxxxxxx>
  • Subject: Re: [netcdfgroup] Ann: NCL/PyNIO now have support for netCDF-4 classic format
  • From: Jeff Whitaker <jswhit@xxxxxxxxxxx>
  • Date: Mon, 27 Aug 2007 09:39:26 -0600
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:

   a = addfile("","c")

You can further specify a compression level:


Similar code exists for PyNIO:

import Nio
opt                  = Nio.options()
opt.Format           = "netcdf4classic"
opt.CompressionLevel = 5

fout = Nio.open_file("","c",opt)

For more information, see the NCL "setfileoption" or PyNIO documentation:

For download:



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.


Jeffrey S. Whitaker         Phone  : (303)497-6313
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