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Re: readcol procedure [message #32069 is a reply to message #32020]

Thu, 12 September 2002 08:43

Liam E. Gumley
Messages: 378
Registered: January 2000

Senior Member

Wayne Landsman wrote:
>
> Reimar Bauer wrote:
>
>> this routine is platform dependent because it uses a unix shell command.
>> I like unix but it's not a problem for idl to determine this itselfs.
>
> numlines.pro (http://idlastro.gsfc.nasa.gov/ftp/pro/misc/numlines.pro called by readcol.pro) only
> spawns to the Unix 'wc' command if !VERSION.OS equals 'unix' (for speed). Otherwise it counts the
> number of lines.
>
>> Perhaps you can try the routine file_line I have defined in 1996 and
>> which was improved later by Paul Krummel. You can find this routine by
>> David at http://www.dfanning.com/tip_examples/file_line.pro
>
> Hmm, I would have thought that reading the entire file into a byte array simply to count the number
> of lines would be overkill. But in my quick tests, file_line.pro does seem to be faster than
> counting the number of lines, and almost as fast (on Unix) as spawning to 'wc'.
>
> I have heard a rumor that there may be a standardized way of counting the number of lines in a file
> in the next release of IDL ;-)

I'm curious: Why does anyone need to count the number of lines in an
ASCII file? If it's to subsequently read the file, then the EOF function
can be used instead to tell you where the input file ends, and it
requires only one pass through the input file. There must be another
application that I don't know about. Or is it just easier to write code
that reads an ASCII file with a known number of lines?

Can anyone enlighten me?

Cheers,
Liam.
Practical IDL Programming
http://www.gumley.com/

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[Message index]

		readcol procedure By: shih I Chun on Tue, 10 September 2002 10:15
		Re: readcol procedure By: Liam E. Gumley on Thu, 12 September 2002 08:43
		Re: readcol procedure By: R.Bauer on Thu, 12 September 2002 11:39
		Re: readcol procedure By: David Fanning on Thu, 12 September 2002 08:59
		Re: readcol procedure By: R.Bauer on Wed, 11 September 2002 23:42
		Re: readcol procedure By: David Fanning on Wed, 11 September 2002 14:12
		Re: readcol procedure By: Wayne Landsman on Wed, 11 September 2002 07:54
		Re: readcol procedure By: R.Bauer on Tue, 10 September 2002 23:33
		Re: readcol procedure By: Don J Lindler on Tue, 10 September 2002 13:30
		Re: readcol procedure By: R.Bauer on Sun, 15 September 2002 08:16
		Re: readcol procedure By: Pavel A. Romashkin on Fri, 13 September 2002 12:30
		Re: readcol procedure By: R.Bauer on Fri, 13 September 2002 10:43
		Re: readcol procedure By: Pavel A. Romashkin on Fri, 13 September 2002 09:36
		Re: readcol procedure By: David Fanning on Fri, 13 September 2002 08:50
		Re: readcol procedure By: Pavel A. Romashkin on Fri, 13 September 2002 08:39
		Re: readcol procedure By: R.Bauer on Thu, 12 September 2002 14:05
		Re: readcol procedure By: Liam E. Gumley on Thu, 12 September 2002 12:11

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