recommender system

import Data.Array import System.IO import System.Random (randomRIO) type Rating = Maybe Int targetRatingsMatrix = [[4,5,4,4,4,4],[3,4,5,4,3,4],[1,2,3,5,5,5],[3,4,5,5,5,4],[4,4,5,5,4,3],[5,5,1,2,1,2]] -- 2 3 transpose:: [[a]]->[[a]] transpose ([]:_) = [] transpose x = (map head x) : transpose (map tail x) mmult :: Num a => [[a]] -> [[a]] -> [[a]] mmult a b = [[ sum $ zipWith (*) ar bc | bc <- (transpose b)] | ar <- a ] makeZeroMatrix :: Int -> Int -> [[Int]] makeZeroMatrix a b = replicate a (replicate b 0) randomList :: Int -> IO([Int]) randomList 0 = return [] randomList n = do r <- randomRIO (1,6) rs <- randomList (n-1) return (r:rs) matrixSize :: [[Int]] -> (Int, Int) matrixSize a = (sum $ map length a, length $ map length a) splitEvery _ [] = [] splitEvery n list = first : (splitEvery n rest) where (first,rest) = splitAt n list randomMatrixHelper :: [[Int]] -> IO([Int]) -> IO([[Int]]) randomMatrixHelper a b = do b' <- b let size = fst (matrixSize a) let a' = concat a let ab = add a' b' return $ splitEvery (fst (matrixSize a)) ab where add :: [Int] -> [Int] -> [Int] add x y = [a+b|a<-x,b<-y] makeRandomMatrix :: Int -> Int -> IO([[Int]]) makeRandomMatrix n m = do let a = makeZeroMatrix n m let b = randomList (fst $ matrixSize a) c <- randomMatrixHelper a b return c