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math.extras: faster search-sorted by bisecting.

db4
John Benediktsson 2013-09-04 21:31:34 -07:00
parent 6e6adb036d
commit f61bf2f4c4
1 changed files with 11 additions and 5 deletions
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16
extra/math/extras/extras.factor
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@ -6,7 +6,7 @@ combinators combinators.short-circuit compression.zlib fry
grouping kernel locals math math.combinatorics math.constants
math.functions math.order math.primes math.ranges
math.ranges.private math.statistics math.vectors memoize random
sequences sequences.extras sets sorting ;
sequences sequences.extras sequences.private sets sorting ;
IN: math.extras
@ -197,11 +197,17 @@ PRIVATE>
: exponential-index ( seq -- x )
dup sum '[ _ / dup ^ ] map-product ;
: search-sorted] ( obj seq -- i )
swap '[ [ _ >= ] find drop dup ] [ length ] bi ? ;
:: search-sorted] ( obj seq -- i )
0 seq length [ 2dup < ] [
2dup + 2/ dup seq nth-unsafe obj before?
[ swap [ nip 1 + ] dip ] [ nip ] if
] while drop ;
: search-sorted) ( obj seq -- i )
swap '[ [ _ > ] find drop dup ] [ length ] bi ? ;
:: search-sorted) ( obj seq -- i )
0 seq length [ 2dup < ] [
2dup + 2/ dup seq nth-unsafe obj after?
[ nip ] [ swap [ nip 1 + ] dip ] if
] while drop ;
: weighted-random ( histogram -- obj )
unzip cum-sum [ last random ] [ search-sorted] ] bi swap nth ;