Hi Jeff,
I have a series of NxM numeric tables I'm doing a quick mean/variance/t-test etcetera on. The cell t1 [i,j] corresponds exactly to the cells t2..N [i,j], and so it's perfectly possible to read one item at a time from each of the 100 files and compute the mean/variance etcetera on all cells that way.
So after mapping openAndProcess, you have a 100xNxM "array" (really a list-of-lists-of-lists), right? And then when you take means and variances, which index are you doing this with respect to? As I read it, you seem to be trying to eliminate the first axis, and end up with an NxM "array". If this is the case, let's say we have mean, variance :: [Double] -> Double openAndProcess :: String -> IO (Matrix String) Here, defining type Matrix a = [[a]] makes it easier to keep the types straight. Then you have these building blocks: (map . map . map) read :: [Matrix String] -> [Matrix Double] transpose2 :: [Matrix Double] -> Matrix [Double] (a couple of lines, maybe even a one-liner, if you use that [a] is a monad) (map . map) mean :: Matrix [Double] -> Matrix Double Composing these gives a function [Matrix String] -> Matrix Double, so once we get to [Matrix String], we're effectively done. you also use map OpenAndProcess :: [String] -> [IO (Matrix String)] You can use sequence to get the IO outside the list, so now you have IO [Matrix String]. All you have to do now is use liftM on your function [Matrix String] -> Matrix Double, which turns it into a function IO [Matrix String] -> IO (Matrix Double). -- Chad Scherrer "Time flies like an arrow; fruit flies like a banana" -- Groucho Marx _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
