21 lines
664 B
Factor
21 lines
664 B
Factor
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USING: kernel namespaces arrays quotations sequences assocs combinators
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mirrors math math.vectors random combinators.cleave macros bake ;
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IN: random-weighted
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: probabilities ( weights -- probabilities ) dup sum [ / ] curry map ;
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: layers ( probabilities -- layers )
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dup length 1+ [ head ] curry* map 1 tail [ sum ] map ;
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: random-weighted ( weights -- elt )
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probabilities layers [ 1000 * ] map 1000 random [ > ] curry find drop ;
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: random-weighted* ( seq -- elt )
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dup [ second ] map swap [ first ] map random-weighted swap nth ;
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MACRO: call-random-weighted ( exp -- )
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[ keys ] [ values <enum> >alist ] bi swap
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[ , random-weighted , case ] bake ;
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