15 Nov
2009
15 Nov
'09
9:50 a.m.
On Sun, Nov 15, 2009 at 03:00:34PM +0300, Alexey Khudyakov wrote:
Naive implementation using lists and index lookup. 2.15 second for 200*200 array
sliceXlist :: Int -> UArr Double -> [UArr Double] sliceXlist n a = map mkSlice [0 .. n-1] where mkSlice x = toU $ map (\y -> indexU a (x + y*n)) [0 .. n-1]
Have you tried something like mkSlice x = mapU (\y -> indexU a (x + y*n)) $ enumFromToU 0 (n-1) I guess it should be a lot faster :). Also, I would recomend using criterion. Another implementation you may try is a' = mapU (\(i :*: x) -> (i `mod` n) :*: x) (indexedU a) mkSlice j = fstU $ filterU (\(i :*: x) -> i == j) a' HTH, -- Felipe.