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Re: Faster way to search/split a string? [message #78454 is a reply to message #78450]

Thu, 24 November 2011 01:15

wlandsman
Messages: 743
Registered: June 2000

Senior Member

Some thoughts (though I am not certain I understand the situation):

1. If you don't need regular expressions then I believe that using STRPOS() is quicker than using STREGEX().
2. If the ID is always in the first 20 characters of ALL_ROWS then I would created a new vector row_id = strmid(all_rows,0,20) and search on that.
3. If the ID is always exactly 20 characters, you could use a program like
http://idlastro.gsfc.nasa.gov/ftp/pro/misc/match.pro to then find the matching indices in row_id and id. This is similar to David's suggestion of sorting and using VALUE_LOCATE.
4. You want to make only a single call to STRSPLIT() for all 10,000 rows. Since IDL V8.0, STRSPLIT returns a list data type when supplied with an array (since in principle each string element could have a different number of "columns"). If you have an earlier version of IDL -- or if this capability is not available in GDL, then I would use the vector capability of STRMID ( http://www.idlcoyote.com/code_tips/strmidvec.html )

--Wayne

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[Message index]

		Re: Faster way to search/split a string? By: rjp23 on Thu, 24 November 2011 06:41
		Re: Faster way to search/split a string? By: rjp23 on Thu, 24 November 2011 06:16
		Re: Faster way to search/split a string? By: wlandsman on Thu, 24 November 2011 01:15
		Re: Faster way to search/split a string? By: David Fanning on Wed, 23 November 2011 10:21
		Re: Faster way to search/split a string? By: Vincent Sarago on Wed, 23 November 2011 10:17
		Re: Faster way to search/split a string? By: Jeremy Bailin on Wed, 23 November 2011 08:02
		Re: Faster way to search/split a string? By: rjp23 on Wed, 23 November 2011 07:37
		Re: Faster way to search/split a string? By: David Fanning on Wed, 23 November 2011 06:40

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