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