diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/PPL/Internal.hs | 29 | ||||
| -rw-r--r-- | src/PPL/Sampling.hs | 21 |
2 files changed, 21 insertions, 29 deletions
diff --git a/src/PPL/Internal.hs b/src/PPL/Internal.hs index b7d49ee..0ba6ae5 100644 --- a/src/PPL/Internal.hs +++ b/src/PPL/Internal.hs @@ -13,6 +13,8 @@ module PPL.Internal randomTree, samples, mutateTree, + splitTrees, + draw, ) where @@ -29,7 +31,10 @@ import qualified System.Random as R -- Reimplementation of the LazyPPL monads to avoid some dependencies -data Tree = Tree !Double [Tree] +data Tree = Tree + { draw :: !Double, + splitTrees :: [Tree] + } split :: Tree -> (Tree, Tree) split (Tree r (t : ts)) = (t, Tree r ts) @@ -41,23 +46,11 @@ randomTree g = let (a, g') = random g in Tree a (randomTrees g') randomTrees g = let (g1, g2) = R.split g in randomTree g1 : randomTrees g2 {-# INLINE mutateTree #-} -mutateTree :: RandomGen g => Double -> Double -> g -> Tree -> Tree -mutateTree p q g (Tree a ts) = - let (r, g1) = random g - (b, g2) = random g1 - in Tree - ( if r >= p - then a - else - if r < p * q - then 1 - a - else b - ) - (mutateTrees p q g2 ts) - where - mutateTrees p q g (t : ts) = - let (g1, g2) = R.split g - in mutateTree p q g1 t : mutateTrees p q g2 ts +mutateTree :: Double -> Tree -> Tree -> Tree -> Tree +mutateTree p (Tree r rs) b@(Tree _ bs) (Tree a ts) = + if r < p + then b + else Tree a $ zipWith3 (mutateTree p) rs bs ts newtype Prob a = Prob {runProb :: Tree -> a} diff --git a/src/PPL/Sampling.hs b/src/PPL/Sampling.hs index ad11837..84e5ada 100644 --- a/src/PPL/Sampling.hs +++ b/src/PPL/Sampling.hs @@ -9,26 +9,25 @@ import Data.Bifunctor import Data.Monoid import Numeric.Log import PPL.Distr -import PPL.Internal hiding (split) -import System.Random (StdGen, random, randoms, split) +import PPL.Internal +import System.Random (StdGen, random, randoms) import qualified Streaming as S import Streaming.Prelude (Stream, yield, Of) -mh :: Monad m => StdGen -> Double -> Double -> Meas a -> Stream (Of (a, Log Double)) m () -mh g p q m = step g2 t x w +mh :: Monad m => StdGen -> Double -> Meas a -> Stream (Of (a, Log Double)) m () +mh g p m = step t0 t x w where - t = randomTree g1 - (g1,g2) = split g + (t0,t) = split $ randomTree g (x, w) = head $ samples m t - step !g !t !x !w = do - let (g1, g2) = split g - t' = mutateTree p q g1 t + step !t0 !t !x !w = do + let (t1:t2:t3:t4:_) = splitTrees t0 + t' = mutateTree p t1 t2 t (x', w') = head $ samples m t' ratio = w' / w - (Exp . log -> r, g3) = random g2 + (Exp . log -> r) = draw t3 (t'', x'', w'') = if r < ratio then (t', x', w') else (t, x, w) yield (x'', w'') - step g3 t'' x'' w'' + step t4 t'' x'' w'' |