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|
{-# LANGUAGE FlexibleContexts #-}
-----------------------------------------------------------------------------
-- |
-- Module : Data.Packed.Vector
-- Copyright : (c) Alberto Ruiz 2007
-- License : GPL-style
--
-- Maintainer : Alberto Ruiz <aruiz@um.es>
-- Stability : provisional
-- Portability : portable
--
-- 1D arrays suitable for numeric computations using external libraries.
--
-- This module provides basic functions for manipulation of structure.
--
-----------------------------------------------------------------------------
module Data.Packed.Vector (
Vector,
fromList, (|>), toList, buildVector,
dim, (@>),
subVector, takesV, join,
mapVector, zipVector, zipVectorWith, unzipVector, unzipVectorWith,
mapVectorM, mapVectorM_, mapVectorWithIndexM, mapVectorWithIndexM_,
foldLoop, foldVector, foldVectorG, foldVectorWithIndex,
successive_, successive
) where
import Data.Packed.Internal.Vector
import Data.Binary
import Foreign.Storable
import Control.Monad(replicateM)
-------------------------------------------------------------------
-- a 64K cache, with a Double taking 13 bytes in Bytestring,
-- implies a chunk size of 5041
chunk :: Int
chunk = 5000
chunks :: Int -> [Int]
chunks d = let c = d `div` chunk
m = d `mod` chunk
in if m /= 0 then reverse (m:(replicate c chunk)) else (replicate c chunk)
putVector v = do
let d = dim v
mapM_ (\i -> put $ v @> i) [0..(d-1)]
getVector d = do
xs <- replicateM d get
return $! fromList xs
instance (Binary a, Storable a) => Binary (Vector a) where
put v = do
let d = dim v
put d
mapM_ putVector $! takesV (chunks d) v
get = do
d <- get
vs <- mapM getVector $ chunks d
return $! join vs
-------------------------------------------------------------------
{- | creates a Vector of the specified length using the supplied function to
to map the index to the value at that index.
@> buildVector 4 fromIntegral
4 |> [0.0,1.0,2.0,3.0]@
-}
buildVector :: Storable a => Int -> (Int -> a) -> Vector a
buildVector len f =
fromList $ map f [0 .. (len - 1)]
-- | zip for Vectors
zipVector :: (Storable a, Storable b, Storable (a,b)) => Vector a -> Vector b -> Vector (a,b)
zipVector = zipVectorWith (,)
-- | unzip for Vectors
unzipVector :: (Storable a, Storable b, Storable (a,b)) => Vector (a,b) -> (Vector a,Vector b)
unzipVector = unzipVectorWith id
-------------------------------------------------------------------
newtype State s a = State { runState :: s -> (a,s) }
instance Monad (State s) where
return a = State $ \s -> (a,s)
m >>= f = State $ \s -> let (a,s') = runState m s
in runState (f a) s'
state_get :: State s s
state_get = State $ \s -> (s,s)
state_put :: s -> State s ()
state_put s = State $ \_ -> ((),s)
evalState :: State s a -> s -> a
evalState m s = fst $ runState m s
newtype MaybeT m a = MaybeT { runMaybeT :: m (Maybe a) }
instance Monad m => Monad (MaybeT m) where
return a = MaybeT $ return $ Just a
m >>= f = MaybeT $ do
res <- runMaybeT m
case res of
Nothing -> return Nothing
Just r -> runMaybeT (f r)
fail _ = MaybeT $ return Nothing
lift_maybe m = MaybeT $ do
res <- m
return $ Just res
-- | apply a test to successive elements of a vector, evaluates to true iff test passes for all pairs
successive_ :: Storable a => (a -> a -> Bool) -> Vector a -> Bool
successive_ t v = maybe False (\_ -> True) $ evalState (runMaybeT (mapVectorM_ step (subVector 1 (dim v - 1) v))) (v @> 0)
where step e = do
ep <- lift_maybe $ state_get
if t e ep
then lift_maybe $ state_put e
else (fail "successive_ test failed")
-- | operate on successive elements of a vector and return the resulting vector, whose length 1 less than that of the input
successive :: (Storable a, Storable b) => (a -> a -> b) -> Vector a -> Vector b
successive f v = evalState (mapVectorM step (subVector 1 (dim v - 1) v)) (v @> 0)
where step e = do
ep <- state_get
state_put e
return $ f ep e
-------------------------------------------------------------------
|
