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random-weighted: add call-random-weighted macro

release
Eduardo Cavazos 2007-09-29 13:28:53 -05:00
parent ce4486d00f
commit 601ae65af6
1 changed files with 8 additions and 4 deletions
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extra/random-weighted/random-weighted.factor
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@ -1,10 +1,10 @@
USING: kernel quotations sequences math math.vectors random ;
USING: kernel namespaces arrays quotations sequences assocs combinators
mirrors math math.vectors random combinators.lib macros bake ;
IN: random-weighted
: probabilities ( weights -- probabilities )
dup sum [ / ] curry map ;
: probabilities ( weights -- probabilities ) dup sum [ / ] curry map ;
: layers ( probabilities -- layers )
dup length 1+ [ head ] curry* map 1 tail [ sum ] map ;
@ -13,4 +13,8 @@ dup length 1+ [ head ] curry* map 1 tail [ sum ] map ;
probabilities layers [ 1000 * ] map 1000 random [ > ] curry find drop ;
: random-weighted* ( seq -- elt )
dup [ second ] map swap [ first ] map random-weighted swap nth ;
dup [ second ] map swap [ first ] map random-weighted swap nth ;
MACRO: call-random-weighted ( exp -- )
[ keys ] [ values <enum> >alist ] bi swap
[ , random-weighted , case ] bake ;