16 lines
422 B
Factor
16 lines
422 B
Factor
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! Haar wavelet transform -- http://dmr.ath.cx/gfx/haar/
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USING: sequences math kernel splitting ;
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IN: math.haar
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: averages ( seq -- seq )
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[ first2 + 2 / ] map ;
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: differences ( seq averages -- differences )
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>r 0 <column> r> [ - ] 2map ;
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: haar-step ( seq -- differences averages )
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2 group dup averages [ differences ] keep ;
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: haar ( seq -- seq )
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dup length 1 <= [ haar-step haar swap append ] unless ;
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