44 lines
1.2 KiB
Haskell
44 lines
1.2 KiB
Haskell
module DataModel where
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import Data.Set (Set)
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import qualified Data.Set as Set
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type Count = Int
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type Frequency = Double
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type Confidence = Double
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class Freq a where
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frequency :: [ItemSet] -> a -> Frequency
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data Item = Item String deriving (Eq, Ord)
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instance Show Item where
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show (Item s) = s --"Item " ++ s
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data ItemSet = ItemSet (Set Item) deriving (Eq, Ord)
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instance Show ItemSet where
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show (ItemSet x) =
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foldr ((\y old -> y ++ " " ++ old).show) "" (Set.toList x)
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instance Freq ItemSet where
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frequency table (ItemSet set) =
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setCount / fromIntegral (length table) where
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setCount = fromIntegral $ count table (ItemSet set)
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count :: [ItemSet] -> ItemSet -> Count
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count table (ItemSet set) =
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length (filter isSuperSet table) where
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isSuperset (ItemSet row) = set `Set.isSubsetOf` row
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data Rule = Rule ItemSet ItemSet deriving (Eq)
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instance Show Rule where
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show (Rule a b) = show a ++ "-> " ++ show b
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instance Freq Rule where
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frequency table (Rule (ItemSet set1) (ItemSet set2)) = frequency table $ ItemSet (set1 `Set.union` set2)
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confidence :: [ItemSet] -> Rule -> Confidence
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confidence table (Rule x y) = frequency table (Rule x y) / frequency table x
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