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Re: edit a large dataset [message #56100 is a reply to message #56095]

Wed, 03 October 2007 07:58

Peter Clinch
Messages: 98
Registered: April 1996

Member

queiny wrote:
> Hi, I have a large dataset (>1e7 records). One field of the record is
> a string 'landuse'. Now I want to add one more field based on the
> 'landuse', i.e., if it is 'forest', then add 'aa', if it is 'urban',
> then add 'bb', etc.. Since there are more than 20 different landuse,
> use 'if-then', or 'case' for each record will be quite inefficient.

I generally find Perl is much better for hacking data sets than IDL,
because systematically fiddling with file contents is what it does very
well. Once it's been suitably butchered, then into IDL for the actual
crunching of numbers that IDL does very well.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/

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[Message index]

		Re: edit a large dataset By: queiny on Wed, 03 October 2007 11:54
		Re: edit a large dataset By: queiny on Wed, 03 October 2007 11:43
		Re: edit a large dataset By: Jean H. on Wed, 03 October 2007 09:29
		Re: edit a large dataset By: Vince Hradil on Wed, 03 October 2007 09:45
		Re: edit a large dataset By: Vince Hradil on Wed, 03 October 2007 09:40
		Re: edit a large dataset By: Peter Clinch on Wed, 03 October 2007 07:58

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