FitnessInput.hs

{-|

  Code to read input data files containing the test inputs and test outputs
  used to evaluate the fitness of individuals.

  Author: mjsottile\@computer.org

-}
module GEP.Examples.Regression.FitnessInput (
  readFitnessInput
) where

import Text.CSV

--
-- assume files have CSV format with a header row where each entry in the
-- header row names a variable.  note that currently we require these to
-- be single characters.  eventually we may automate the process of mapping
-- variables onto characters in the genome to allow more expressive names
-- to be associated with variables.
--

type FitnessDict = [[(Char,Double)]]

dictify :: Record -> [Record] -> (FitnessDict, [Double])
dictify lbls values =
    (map (\j -> zip (init charLbls) j) (init floatValues),
     map last floatValues)
    where
      charLbls = map head lbls  -- First line contains Terminal chars.
      floatValues = map toDoubles (filter emptyRecord values)
      emptyRecord :: [Field] -> Bool
      emptyRecord r = 0 < (length . concat) r
      toDoubles :: Record -> [Double]
      toDoubles = map read

-- function that takes a filename and returns a dictionary
readFitnessInput :: String -> IO (FitnessDict,[Double])
readFitnessInput fname = do
    result <- parseCSVFromFile fname
    case result of Left err -> error $ "Bad regression fitness input: "
                                 ++ show fname ++ "!\n" ++ show err
                   Right xs -> return $ dictify (head xs) (tail xs)

{-
main :: IO ()
main = do
  x <- readFitnessInput "test.csv"
  print x
-}