Custom Query (35 matches)

Issac Trotts <issac@…> reports: empty array equals non-empty array

Prelude Data.Array.Repa> import Data.Array.Repa as R
Prelude Data.Array.Repa> let x :: Array DIM1 Int; x = fromList (Z :. (0::Int)) []
Prelude Data.Array.Repa> let y :: Array DIM1 Int; y = fromList (Z :. (1::Int)) [1]
Prelude Data.Array.Repa> x == y
True
Prelude Data.Array.Repa> y == x
*** Exception: Data.Array.Repa.Operators.IndexSpace.reshape: reshaped array will not match size of the original

Make sure this works in Repa3.

If we want to compute something like the mandelbrot set, each pixel can take a different time to compute. Want a work queue and some sort of hint system to tell Repa how to partition the array into chunks.

import Data.Array.Repa

arr :: Array U DIM2 Int
arr = fromListUnboxed (Z :. 5 :. 5) [1..25]

combined :: Array U DIM2 Int
combined 
  = computeP $ traverse arr (\_ -> Z :. 4 :. 4 :: DIM2) 
  $ \f (Z :. x :. y) -> sumAllS $ extract f (x,y) (2,2)

extract :: (DIM2 -> Int) -> (Int,Int) -> (Int,Int) -> Array D DIM2 Int
extract lookup (x0,y0) (width,height) 
  = fromFunction bounds 
  $ \sh -> offset lookup sh
    where 
    bounds = Z :. width :. height
    offset :: (DIM2 -> Int) -> DIM2 -> Int
    offset f (Z :. x :. y) = f (Z :. x + x0 :. y + y0)

main = print combined