Revision: 865
http://assorted.svn.sourceforge.net/assorted/?rev=865&view=rev
Author: yangzhang
Date: 2008-07-02 12:50:18 -0700 (Wed, 02 Jul 2008)
Log Message:
-----------
added newbie normalization programs
Added Paths:
-----------
sandbox/trunk/src/hs/Normalize0.lhs
sandbox/trunk/src/hs/Normalize1.lhs
sandbox/trunk/src/hs/Normalize2.lhs
Added: sandbox/trunk/src/hs/Normalize0.lhs
===================================================================
--- sandbox/trunk/src/hs/Normalize0.lhs (rev 0)
+++ sandbox/trunk/src/hs/Normalize0.lhs 2008-07-02 19:50:18 UTC (rev 865)
@@ -0,0 +1,46 @@
+#!/usr/bin/env runhaskell
+
+This is one of my first attempts at writing Haskell. This sandbox contains
+three iterations of this program, which I went through while taking suggestions
+from people in #haskell.
+
+For each line from stdin, normalize the second field
+against the value specified on the command line.
+
+E.g., for input:
+ 1 200 lowest
+ 2 400 highest
+ 3 300
+ 4 400
+
+normalize should output:
+ 1 0.5 lowest
+ 2 1.0 highest
+ 3 0.75
+ 4 1.0
+
+> import System (getArgs)
+>
+> main = do
+> argv <- getArgs
+> interact $ (processLines (argv !! 0) (argv !! 1) (argv !! 2)) . lines
+> -- interact $ (uncurry processLines (take 3 argv)) . lines
+> -- getArgs >>= \argv -> (interact $ unlines . (processLines (head argv)) . lines)
+>
+> processLines operation max1 max2 ls = if operation == "max"
+> then show getMax
+> else unlines $ map normLine ls
+> where normLine = unwords . normWords . words
+> normLine :: String -> String
+> normWords ws = [head ws, normNumber ws] ++ (getRest ws)
+> normWords :: [String] -> [String]
+> getNumber = read . head . tail
+> getNumber :: [String] -> Double
+> getRest = drop 2
+> getRest :: [a] -> [a]
+> normNumber = show . (/ maxNumber) . getNumber
+> normNumber :: [String] -> String
+> maxNumber = max (read max1) (read max2)
+> maxNumber :: Double
+> getMax = maximum . (map (getNumber . words)) $ ls
+> getMax :: Double
Added: sandbox/trunk/src/hs/Normalize1.lhs
===================================================================
--- sandbox/trunk/src/hs/Normalize1.lhs (rev 0)
+++ sandbox/trunk/src/hs/Normalize1.lhs 2008-07-02 19:50:18 UTC (rev 865)
@@ -0,0 +1,35 @@
+#!/usr/bin/env runhaskell
+
+For each line from stdin, normalize the second (0-indexed) field
+against the value specified on the command line.
+
+E.g., for input:
+ 1 200 lowest
+ 2 400 highest
+ 3 300
+ 4 400
+
+normalize 1 400 should output:
+ 1 0.5 lowest
+ 2 1.0 highest
+ 3 0.75
+ 4 1.0
+
+> import System (getArgs)
+>
+> main = do
+> argv <- getArgs
+> interact $ (processLines (read (argv !! 0)) (read (argv !! 1))) . lines
+>
+> processLines :: Int -> Float -> [String] -> String
+> processLines index maxNumber ls = unlines $ map normLine ls
+> where normLine :: String -> String
+> normLine = unwords . normWords . words
+> normWords :: [String] -> [String]
+> normWords ws = before ++ middle ++ after
+> where before :: [String]
+> before = take index ws
+> middle :: [String]
+> middle = [show . (/ maxNumber) . read $ ws !! index]
+> after :: [String]
+> after = drop (index + 1) ws
Added: sandbox/trunk/src/hs/Normalize2.lhs
===================================================================
--- sandbox/trunk/src/hs/Normalize2.lhs (rev 0)
+++ sandbox/trunk/src/hs/Normalize2.lhs 2008-07-02 19:50:18 UTC (rev 865)
@@ -0,0 +1,35 @@
+#!/usr/bin/env runhaskell
+
+For each line from stdin, normalize the second (0-indexed) field
+against the value specified on the command line.
+
+E.g., for input:
+ 1 200 lowest
+ 2 400 highest
+ 3 300
+ 4 400
+
+normalize 1 400 should output:
+ 1 0.5 lowest
+ 2 1.0 highest
+ 3 0.75
+ 4 1.0
+
+> import System (getArgs)
+>
+> main = do
+> [arg0, arg1] <- getArgs
+> interact $ normalize (read arg0) (read arg1)
+>
+> normalize :: Int -> Float -> String -> String
+> normalize index maxNumber = processLines (processField index (/ maxNumber))
+>
+> processLines :: ([[String]] -> [[String]]) -> String -> String
+> processLines f = unlines . (map unwords) . f . (map words) . lines
+>
+> processField :: (Read a, Show a) => Int -> (a -> a) -> [[String]] -> [[String]]
+> processField index f = map (mapAt index (show . f . read))
+>
+> mapAt :: Int -> (a -> a) -> [a] -> [a]
+> mapAt index f ws = before ++ (f middle) : after
+> where (before, middle : after) = splitAt index ws
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