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Re: IDL 8.2.2 released [message #83261 is a reply to message #83056]

Wed, 13 February 2013 02:04

Fabzi
Messages: 305
Registered: July 2010

Senior Member

Hi Timothy

On 02/13/2013 01:43 AM, timothyja123@gmail.com wrote:
> I have been looking into your NetCDF suggestion.
>
> I have hit a problem however in that the IDL library
> does not seem to have an option to compress the NetCDF files.

Which version of IDL are you using? With 7.1.1 (patched for netCDF) and
higher this should be no problem. But you have to specify that you want
to use netCDF 4 when creating the file, with the /NETCDF4_FORMAT
keyword: http://www.exelisvis.com/docs/NCDF_CREATE.html

NetCDF4 allows you to create files larger than 2gb (upper limit for
netCDF3 files) and also to use the three compression keywords when
defining a variable (GZIP, CHUNCK_DIMENSIONS, SHUFFLE):
http://www.exelisvis.com/docs/NCDF_VARDEF.html

NetCDF is very fast, but the more you compress, the slowier it will be
though. I found almost no win in file size when going from GZIP=5 to
GZIP=9 so I suggest to stick by 5. I also noticed that creating
compressed files takes longer but that reading them is almost as fast as
uncompressed ones, but this should be tested in a proper benchmark. The
compression will be very efficient if your data is very recurrent (many
zeros for example).

And again, I highly recommend David's NCDF_FILE object, which makes it
much more fun to work with ncdf files and has no limitations (all
keywords are accessible):
http://www.idlcoyote.com/programs/ncdf_file__define.pro
(the only drawback of David's tool is that it is "all objects" and
therefore parsing a lot of files having a lot of variables/attributes is
a bit slow)

Cheers,

Fab

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[Message index]

		IDL 8.2.2 released By: Mark Piper on Tue, 05 February 2013 09:39
		Re: IDL 8.2.2 released By: David Fanning on Wed, 06 February 2013 16:24
		Re: IDL 8.2.2 released By: Mark Piper on Thu, 07 February 2013 08:16
		Re: IDL 8.2.2 released By: Mark Piper on Wed, 06 February 2013 16:09
		Re: IDL 8.2.2 released By: tom.grydeland on Wed, 20 March 2013 02:58
		Re: IDL 8.2.2 released By: Mark Piper on Wed, 06 February 2013 16:00
		Re: IDL 8.2.2 released By: Matt[2] on Thu, 07 February 2013 08:20
		Re: IDL 8.2.2 released By: Mark Piper on Wed, 06 February 2013 15:23
		Re: IDL 8.2.2 released By: Bob[4] on Wed, 06 February 2013 13:23
		Re: IDL 8.2.2 released By: Bob[4] on Thu, 07 February 2013 10:53
		Re: IDL 8.2.2 released By: dain.cilke on Thu, 07 February 2013 14:07
		Re: IDL 8.2.2 released By: Louis Giglio on Wed, 06 February 2013 13:01
		Re: IDL 8.2.2 released By: Andy Sayer on Thu, 07 February 2013 06:22
		Re: IDL 8.2.2 released By: Fabzi on Wed, 06 February 2013 11:18
		Re: IDL 8.2.2 released By: David Fanning on Wed, 06 February 2013 10:24
		Re: IDL 8.2.2 released By: Mark Piper on Wed, 06 February 2013 09:20
		Re: IDL 8.2.2 released By: Mark Piper on Wed, 06 February 2013 09:18
		Re: IDL 8.2.2 released By: David Fanning on Wed, 06 February 2013 06:51
		Re: IDL 8.2.2 released By: Fabzi on Wed, 06 February 2013 06:37
		Re: IDL 8.2.2 released By: lecacheux.alain on Wed, 06 February 2013 04:29
		Re: IDL 8.2.2 released By: Fabzi on Wed, 06 February 2013 01:44
		Re: IDL 8.2.2 released By: wlandsman on Tue, 05 February 2013 23:29
		Re: IDL 8.2.2 released By: David Fanning on Tue, 05 February 2013 15:06
		Re: IDL 8.2.2 released By: wlandsman on Tue, 05 February 2013 14:28
		Re: IDL 8.2.2 released By: timothyja123 on Sat, 09 February 2013 02:44
		Re: IDL 8.2.2 released By: Matt Haffner on Fri, 08 February 2013 13:48
		Re: IDL 8.2.2 released By: Michael Galloy on Wed, 13 February 2013 16:19
		Re: IDL 8.2.2 released By: Mark Piper on Wed, 20 March 2013 14:10
		Re: IDL 8.2.2 released By: Fabzi on Fri, 08 February 2013 09:15
		Re: IDL 8.2.2 released By: Fabzi on Fri, 08 February 2013 09:04
		Re: IDL 8.2.2 released By: timothyja123 on Tue, 12 February 2013 16:43
		Re: IDL 8.2.2 released By: dain.cilke on Fri, 08 February 2013 08:24
		Re: IDL 8.2.2 released By: chris_torrence@NOSPAM on Fri, 08 February 2013 08:14
		Re: IDL 8.2.2 released By: Bob[4] on Thu, 07 February 2013 14:55
		Re: IDL 8.2.2 released By: dain.cilke on Thu, 07 February 2013 14:10
		Re: IDL 8.2.2 released By: Bob[4] on Thu, 07 February 2013 12:14
		Re: IDL 8.2.2 released By: David Fanning on Thu, 07 February 2013 11:15
		Re: IDL 8.2.2 released By: chris_torrence@NOSPAM on Thu, 07 February 2013 09:11
		Re: IDL 8.2.2 released By: Mark Piper on Thu, 07 February 2013 08:55
		Re: IDL 8.2.2 released By: David Fanning on Thu, 07 February 2013 08:21
		Re: IDL 8.2.2 released By: Mark Piper on Thu, 14 February 2013 08:23
		Re: IDL 8.2.2 released By: Michael Galloy on Wed, 13 February 2013 16:16
		Re: IDL 8.2.2 released By: timothyja123 on Wed, 13 February 2013 14:52
		Re: IDL 8.2.2 released By: Fabzi on Wed, 13 February 2013 02:04
		Re: IDL 8.2.2 released By: lecacheux.alain on Wed, 20 March 2013 09:07
		Re: IDL 8.2.2 released By: tom.grydeland on Thu, 21 March 2013 02:38
		Re: IDL 8.2.2 released By: Mark Piper on Thu, 21 March 2013 09:41
		Re: IDL 8.2.2 released By: chris_torrence@NOSPAM on Mon, 15 April 2013 21:08
		Re: IDL 8.2.2 released By: tom.grydeland on Fri, 26 April 2013 03:06
		Re: IDL 8.2.2 released By: chris_torrence@NOSPAM on Fri, 26 April 2013 14:33
		Re: IDL 8.2.2 released By: tushar on Thu, 25 April 2013 23:31

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