Re: [Haskell-beginners] reorganizing lists

So I have a text full of x and y coordinates in the for x_y new line delimited. Here is the first 3 lines: 68_1 153_16099247764943158 153_775041589 I'm massaging the data to run a liner regression on it. At the moment the program I'm writing looks like this (still a work in progress...): module Main where import qualified Data.Text as T import qualified Data.Text.IO as TI import Numeric.GSL.Fitting.Linear import Data.Packed.Vector buildList :: IO [[T.Text]] buildList = TI.readFile "lin_reg_data.txt" >>= return . map (T.split (=='_')) . T.lines --main :: IO () --main = do -- values <- buildList -- let heads = fromList $ map (\x -> read (T.unpack . head $ x):: Double) values -- let lasts = fromList $ map (\x -> read (T.unpack . last $ x):: Double) values -- print linear heads lasts I'm just trying to find a way to not iterate over "vaues" twice as that seems like a waste of computing time to me. Of course any advice on this would be appreciated. Bryce On 01/28/2013 10:42 AM, Ozgur Akgun wrote:

Hi,

On 28 January 2013 18:37, Bryce Verdier mailto:bryceverdier@gmail.com> wrote:

I know I can do this with calling 2 maps on the container, but I would also like to do this in one iteration.

As a learning experience, may I suggest you post the code you would have written with two maps? Then we can try and improve on that to have only one map.

Best,

-- Ozgur Akgun

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