diff options
Diffstat (limited to 'src/PPL/Sampling.hs')
| -rw-r--r-- | src/PPL/Sampling.hs | 21 |
1 files changed, 10 insertions, 11 deletions
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'' |