31 lines
707 B
Factor
31 lines
707 B
Factor
! Copyright (C) 2012 John Benediktsson
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! See http://factorcode.org/license.txt for BSD license
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USING: kernel math math.functions math.statistics math.vectors
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sequences sequences.extras ;
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IN: math.similarity
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: euclidian-similarity ( a b -- n )
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v- norm 1 + recip ;
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: pearson-similarity ( a b -- n )
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over length 3 < [ 2drop 1.0 ] [ population-corr 0.5 * 0.5 + ] if ;
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: cosine-similarity ( a b -- n )
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[ v. ] [ [ norm ] bi@ * ] 2bi / ;
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<PRIVATE
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: weighted-v. ( w a b -- n )
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[ * * ] [ + ] 3map-reduce ;
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: weighted-norm ( w a -- n )
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[ absq * ] [ + ] 2map-reduce ;
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PRIVATE>
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: weighted-cosine-similarity ( w a b -- n )
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[ weighted-v. ]
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[ overd [ weighted-norm ] 2bi@ * ] 3bi / ;
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