Comparing big lists

[Gregory Lypny]

Hi Everyone,

	Thought I would pick your brains on the topic of comparing two big 
lists.  Both are tab delimited.  bigList has about 100,000 lines and 6 
items (columns) per line.  smallList is about 15,000 lines and 2 items 
per line.  I want to identify the lines in bigList in which the third 
item is the same as the second item in a line in smallList, and then 
pull out the intersection.  I used something like this, which works fine.

	set the itemDelimiter to tab
			repeat for each line j of smallList
				put lineOffset(item 2 of j, bigList) into thisLine
				if thisLine is not 0 then put j & tab & \
					 line thisLine of bigList  & return after mergedList
			end repeat
	delete last character of mergedList  -- Get rid of the trailing Return

Using the lineOffset function seemed the obvious choice to me, but I'm 
also interested in other approaches.

	Regards,

		Greg


Gregory Lypny
Associate Professor
John Molson School of Business
Concordia University
_________________________
"Absence of evidence is not evidence of absence."
                 - Anonymous

http://rubbersoul.concordia.ca
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