[Assorted-commits] SF.net SVN: assorted: [865] sandbox/trunk/src/hs

[<yan...@us...>]

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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