module Aux (redAtt, selavN, gtAtec ) where

-- (c) 2007 Hans van Thiel
-- Version 0.1 License GPL

import Reduce ( redCons )
import Data.Array
import Data.List ( delete )

-- module: auxiliary functions for Main

-- reduction for a consequent attribute, coded by Codec

-- execute the reduction on all attribute-value pairs
-- the result matches each reduction with its consequent

redAtt :: [(Int,Int)] -> [[(Int,Int)]] -> [([[(Int,Int)]], (Int,Int))]
redAtt avls src = zip (map ((flip redCons) src) avls) avls
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-- get the index of an attribute string

selAtt :: String -> Array Int [String] -> Int
selAtt att attvarr  = slAtt att (indices attvarr) attvarr where
                            slAtt at [] arr = error "Attribute not found..."
                            slAtt at (x:xs) arr | att == (head (arr ! x)) = x
                                                | otherwise = slAtt at xs arr

-- get the coded attribute-value pairs from the attribute index

selAV :: Int -> Array Int [String] -> [(Int,Int)]
selAV ai attvarr = let avstr = attvarr ! ai
                       vais = [1..(length avstr)-1]
                   in  [(ai, x) | x <- vais ]

-- get the coded attribute-value pairs from the attribute name

selavN :: String -> Array Int [String] -> [(Int,Int)]
selavN atn attvarr = selAV ai attvarr where ai = selAtt atn attvarr

-- get antecedent and consequent attribute indices from consequent index

gtAtec :: Int -> Array Int [String] -> ([Int],Int)
gtAtec cns attvarr = ((delete cns ils),cns) where
                                 ils = indices attvarr              
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