split filtering into phase 3

phase3.hs

@@ -0,0 +1,39 @@
+import CSVParser
+import DataModel
+import ExtractRules
+import qualified Data.Set as Set
+import qualified Data.List as List
+import System.Environment(getArgs)
+import Control.Monad(when)
+
+main :: IO()
+main = do
+    args <- getArgs
+    when (3 > length args) (error "Usage: phase3 table.csv rules.csv count [bestRules.csv]")
+    let bestRuleCount = read $ args !! 2
+    tableFile <- readFile $ head args
+    rulesFile <- readFile $ args !! 1
+    case parseCSV tableFile of
+        Left _ -> error "Could not parse table"
+        Right tableFileContent ->
+            case parseCSV rulesFile of
+                Left _ -> error "Could not parse frequent patterns"
+                Right rulesFileContent -> do
+                    print $ output
+                    when (length args > 3) $
+                        writeFile (args !! 3) output
+                    where
+                    table = map (ItemSet. Set.fromList .map Item) tableFileContent
+                    rules = map ruleFromRow rulesFileContent
+                    bestRules = take bestRuleCount $ List.sortBy (\x y -> compare (lift table y) (lift table x)) rules
+                    output = formatToCSV bestRules
+
+formatToCSV :: [Rule] -> String
+formatToCSV = foldr (\x old -> old ++ formatRow x ++ "\n") "" where
+    formatRow (Rule x y) = show x ++ ", ," ++ show y
+
+ruleFromRow :: [String] -> Rule
+ruleFromRow columns = Rule item1 item2
+    where
+    item1 = ItemSet $ Set.fromList $ map Item $ takeWhile (/= " ") columns
+    item2 = ItemSet $ Set.fromList $ map Item $ tail $ dropWhile (/= " ") columns