Path: utzoo!utgpu!water!ljdickey
From: ljdickey@water.waterloo.edu (Lee Dickey)
Newsgroups: comp.lang.apl
Subject: MODE
Keywords: mode
Message-ID: <1428@water.waterloo.edu>
Date: 24 Feb 88 14:30:19 GMT
Reply-To: ljdickey@water.waterloo.edu (Lee Dickey)
Organization: U. of Waterloo, Ontario
Lines: 26


 A few weeks ago someone posted an article asking about an
 efficient ways to calculate the mode of an array of numbers.
 I guess I'll stick my neck out and suggest this algorithm.
 I don't know if this is best, but I think this works:


	NUB	<-  ( ( X iota X ) =  iota rho X ) /x <- ,x

	FREQ	<-  +/ NUB jot.= X

	Z	<-  1 take ( FREQ = max/ FREQ ) / NUB

 Of course in the last line it would be better to replace the
 "1 take" by "MIDDLE", where MIDDLE is the function that selects
 the middle element of a sorted vector, but I think that is another
 topic...

 Sorry, but I lost the name and address of the original poster, so
 can not send mail.  I would be interested in seeing other solutions.

-- 
 L. J. Dickey, Faculty of Mathematics, University of Waterloo.
	ljdickey@water.waterloo.edu
	ljdickey@watdcs.BITNET
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