Updated README, added Ch02 content

Ch01/README.md

@@ -7,18 +7,19 @@ Refer to the book for step-by-step explanations.
 <p align="center"><a href="http://haskelldata.com" target="_blank"><img src="http://haskelldata.com/images/ch01.png"/></a></p>
 
 # Recipes
-* **Code01**: Accumulating text data from a file path
-* **Code02**: Catching I/O code faults
-* **Code03**: Keeping and representing data from a CSV file
-* **Code04**: Examining a JSON file with the aeson package
-* **Code05**: Reading an XML file using the HXT package
-* **Code06**: Capturing table rows from an HTML page
-* **Code07**: Understanding how to perform HTTP GET requests
-* **Code08**: Learning how to perform HTTP POST requests
-* **Code09**: Traversing online directories for data
-* **Code10**: Using MongoDB queries in Haskell
-* **Code11**: Reading from a remote MongoDB server
-* **Code12**: Exploring data from a SQLite database
+* **Code01**: Harnessing data from various sources *(not included)*
+* **Code02**: Accumulating text data from a file path
+* **Code03**: Catching I/O code faults
+* **Code04**: Keeping and representing data from a CSV file
+* **Code05**: Examining a JSON file with the aeson package
+* **Code06**: Reading an XML file using the HXT package
+* **Code07**: Capturing table rows from an HTML page
+* **Code08**: Understanding how to perform HTTP GET requests
+* **Code09**: Learning how to perform HTTP POST requests
+* **Code10**: Traversing online directories for data
+* **Code11**: Using MongoDB queries in Haskell
+* **Code12**: Reading from a remote MongoDB server
+* **Code13**: Exploring data from a SQLite database
 
 # How to use
 ### Setting up the environment

Ch02/Code01_whitespace/Code0201.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0201.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0201
+version:             0.1.0.0
+synopsis:            Trimming excess whitespace.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Text
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0201
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code01_whitespace/Main.hs

@@ -0,0 +1,9 @@
+import Data.Char (isSpace)
+
+-- Trims whitespace
+trim :: String -> String
+trim = f . f
+  where f = reverse . dropWhile isSpace
+
+main :: IO ()
+main = putStrLn $ trim " wahoowa! "

Ch02/Code01_whitespace/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0201 *~ 

Ch02/Code02_punctuation/Code0202.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0202.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0202
+version:             0.1.0.0
+synopsis:            Ignoring punctuation and special characters
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Text
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0202
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7, MissingH >=1.2 && <1.3
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code02_punctuation/Main.hs

@@ -0,0 +1,17 @@
+-- Cleans up a sentence
+main :: IO ()
+main = do
+  let quote = "Deep Blue plays very good chess-so what?\
+              \Does that tell you something about how we play chess?\
+              \ No. Does it tell you about how Kasparov envisions,\
+              \ understands a chessboard? (Douglas Hofstadter)"
+  putStrLn $ (removePunctuation.replaceSpecialSymbols) quote
+
+-- Removes punctuation
+punctuations = ['!', '"', '#', '$', '%', '(', ')', '.', ',', '?']  
+removePunctuation = filter (`notElem` punctuations)
+
+-- Replaces some symbols with a space
+specialSymbols = ['/', '-']
+replaceSpecialSymbols = map $ (\c -> if c `elem` specialSymbols 
+                                     then ' ' else c)

Ch02/Code02_punctuation/Main2.hs

@@ -0,0 +1,15 @@
+import Data.String.Utils (replace)
+
+-- Cleans up a sentence
+main :: IO ()
+main = do
+  let quote = "Deep Blue plays very good chess-so what? Does that tell you something about how we play chess? No. Does it tell you about how Kasparov envisions, understands a chessboard? (Douglas Hofstadter)"
+  print $ (removePunctuation.replaceSpecialSymbols) quote
+
+-- Removes punctuation using the `replace` function  
+removePunctuation = foldr (.) id $ map (flip replace "") 
+        ["!", "\"", "#", "$", "%", "(", ")", ".", ",", "?"]
+
+-- Replaces some symbols with a space using `replace`       
+replaceSpecialSymbols = foldr (.) id $ map (flip replace " ") 
+        ["/", "-"]

Ch02/Code02_punctuation/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0202 *~ 

Ch02/Code03_unexpected/Code0203.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0203.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0203
+version:             0.1.0.0
+synopsis:            Coping with unexpected or missing input.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Text
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0203
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7, csv >=0.1 && <0.2
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code03_unexpected/Main.hs

@@ -0,0 +1,36 @@
+import Text.CSV
+
+data Laptop = Laptop { brand :: Maybe String
+                     , model :: Maybe String
+                     , cost :: Maybe Float
+                     } deriving Show
+
+-- Parses an incomplete CSV
+main :: IO ()
+main = do
+  let fileName = "input.csv"
+  input <- readFile fileName
+  let csv = parseCSV fileName input
+  let laptops = parseLaptops csv
+  print laptops
+  
+parseLaptops (Left err) = []
+parseLaptops (Right csv) = 
+  foldl (\a record -> if length record == 3
+                      then (parseLaptop record):a
+                      else a) [] csv
+
+parseLaptop record = Laptop { brand = getBrand $ record !! 0,
+                              model = getModel $ record !! 1, 
+                              cost = getCost $ record !! 2 }
+  
+getBrand :: String -> Maybe String
+getBrand str = if null str then Nothing else Just str
+
+getModel :: String -> Maybe String
+getModel str = if null str then Nothing else Just str
+
+getCost :: String -> Maybe Float
+getCost str = case reads str::[(Float,String)] of
+  [(cost, "")] -> Just cost
+  _ -> Nothing

Ch02/Code03_unexpected/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0203 *~ 

Ch02/Code03_unexpected/input.csv

@@ -0,0 +1,3 @@
+Lenovo Thinkpad,T540p,832.15
+Lenovo Thinkpad,X1 Carbon,
+Lenovo IdeaPad,,949.00

Ch02/Code04_regex/Code0204.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0204.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0204
+version:             0.1.0.0
+synopsis:            Regular expression example.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Text
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0204
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7, regex-posix >=0.95 && <0.96
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code04_regex/Main.hs

@@ -0,0 +1,25 @@
+import Text.Regex.Posix ((=~))
+
+looksLikeName :: String -> Bool
+looksLikeName str = str =~ "^[A-Z][a-z]{1,30}$" :: Bool
+
+punctuations = ['!', '"', '#', '$', '%', '(', ')', '.', ',', '?']  
+removePunctuation = filter (`notElem` punctuations)
+
+specialSymbols = ['/', '-']
+replaceSpecialSymbols = map $ (\c -> if c `elem` specialSymbols
+                                     then ' ' else c)
+
+createTuples (x:y:xs) = (x ++ " " ++ y) : createTuples (y:xs)
+createTuples _ = []
+
+-- Matches a regular expression to find names
+main :: IO ()
+main = do
+  input <- readFile "input.txt"
+  let cleanInput = (removePunctuation.replaceSpecialSymbols) input
+  let wordPairs = createTuples $ words cleanInput
+  let possibleNames = 
+        filter (all looksLikeName . words) wordPairs
+  print possibleNames
+

Ch02/Code04_regex/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0204 *~ 

Ch02/Code04_regex/input.txt

@@ -0,0 +1 @@
+Other co-authors of Dr. Erickson's include Mark Norell, chairman of paleontology at the American Museum of Natural History; Philip Currie, a professor of dinosaur paleobiology at the University of Alberta; and Peter Makovicky, associate curator of paleontology at the Field Museum in Chicago.

Ch02/Code05_lex/Code0205.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0205.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0205
+version:             0.1.0.0
+synopsis:            Parsing an email address.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Text
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0205
+  main-is:             Main.hs
+  -- other-modules:       
+  other-extensions:    OverloadedStrings
+  build-depends:       base >=4.6 && <4.7, attoparsec >=0.10 && <0.11
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code05_lex/Main.hs

@@ -0,0 +1,23 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+import Data.Attoparsec.Text
+import Data.Char (isSpace, isAlphaNum)
+
+data Email = Email 
+  { user :: String
+  , host :: String
+  } deriving Show
+
+email :: Parser Email
+email = do
+  skipSpace
+  user <- many' $ satisfy isAlphaNum
+  at <- char '@'
+  hostName <- many' $ satisfy isAlphaNum
+  period <- char '.'
+  domain <- many' (satisfy isAlphaNum)
+  return $ Email user (hostName ++ "." ++ domain)
+  
+-- Lexes and parses an email address
+main :: IO ()
+main = print $ parseOnly email "nishant@shukla.io"

Ch02/Code05_lex/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0205 *~ 

Ch02/Code06_combining/Code0206.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0206.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0206
+version:             0.1.0.0
+synopsis:            Combining data records together.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Data
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0206
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7, csv >=0.1 && <0.2, containers >=0.5 && <0.6
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code06_combining/Main.hs

@@ -0,0 +1,40 @@
+import Text.CSV (parseCSV, Record)
+import Data.Map (fromListWith)
+import Control.Applicative ((<|>))
+
+data Item = Item { name :: String
+                 , color :: String
+                 , cost :: Maybe Float
+                 } deriving Show
+
+-- Combines CSV fields from duplicated data
+main :: IO ()
+main = do
+  let fileName = "input.csv"
+  input <- readFile fileName
+  let csv = parseCSV fileName input
+  either handleError doWork csv
+
+handleError = print
+
+doWork :: [Record] -> IO ()
+doWork csv = print $ fromListWith combine $ map parseToTuple csv
+
+combine :: Item -> Item -> Item
+combine item1 item2 = Item { name = name item1
+                           , color = color item1 <|> color item2
+                           , cost = cost item1 <|> cost item2 }
+
+parseToTuple :: Record -> (String, Item)
+parseToTuple record = (name item, item) 
+  where item = parseItem record
+
+parseItem :: Record -> Item
+parseItem record = 
+  Item { name = record !! 0
+       , color = record !! 1
+       , cost = case reads (record !! 2)::[(Float,String)] of
+          [(c, "")] -> Just c
+          _ -> Nothing 
+       }
+

Ch02/Code06_combining/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0206 *~ 

Ch02/Code06_combining/input.csv

@@ -0,0 +1,6 @@
+glasses,,60.00
+jacket,brown,
+shirt,,
+glasses,black,
+jacket,,89.99
+shirt,red,15.00

Ch02/Code07_dedup/Code0207.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0207.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0207
+version:             0.1.0.0
+synopsis:            Deduplicating conflicting data.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Data
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0207
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7, csv >=0.1 && <0.2, containers >=0.5 && <0.6
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code07_dedup/Main.hs

@@ -0,0 +1,47 @@
+import Text.CSV (parseCSV, Record)
+import Data.Map (fromListWith)
+import qualified Data.Set as S
+
+data Artist = Artist { name :: String
+                     , song :: S.Set String
+                     , genre :: S.Set String
+                     } deriving Show
+
+-- Combines duplicated CSV data into a set
+main :: IO ()
+main = do
+  let fileName = "input.csv"
+  input <- readFile fileName
+  let csv = parseCSV fileName input
+  either handleError doWork csv
+
+handleError = print
+
+doWork :: [Record] -> IO ()
+doWork csv = print $ fromListWith combine $ map parseToTuple csv
+
+combine :: Artist -> Artist -> Artist
+combine artist1 artist2 = 
+  Artist { name = name artist1
+         , song = S.union (song artist1) (song artist2)
+         , genre = S.union (genre artist1) (genre artist2) }
+                          
+parseToTuple :: [String] -> (String, Artist)
+parseToTuple record = (name item, item) 
+  where item = parseItem record
+
+parseItem :: Record -> Artist
+parseItem record = 
+  Artist { name = nameStr
+         , song = if null songStr 
+                  then S.empty 
+                  else S.singleton songStr
+         , genre = if null genreStr 
+                   then S.empty 
+                   else S.singleton genreStr
+         }
+  where nameStr  = record !! 0
+        songStr = record !! 1
+        genreStr  = record !! 2
+
+                            

Ch02/Code07_dedup/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0207 *~ 

Ch02/Code07_dedup/input.csv

@@ -0,0 +1,6 @@
+Daft Punk,Around the World,French house
+Madeon,Icarus,French house
+Daft Punk,Get Lucky,
+Justice,Genesis,Electro
+Junior Boys,Bits & Pieces,Synthpop
+Justice,,Electronic rock

Ch02/Code08_freq/Code0208.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0208.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0208
+version:             0.1.0.0
+synopsis:            Creating a frequency map.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Data
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0208
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code08_freq/Main.hs

@@ -0,0 +1,10 @@
+import Data.List (group, sort)
+
+data Color = Red | Green | Blue deriving (Show, Ord, Eq)
+
+-- Generates a frequency map from a list of items
+main :: IO ()
+main = do
+  let items = [Red, Green, Green, Blue, Red, Green, Green]
+  let freq = map (\x -> (head x, length x)) . group . sort $ items
+  print freq

Ch02/Code08_freq/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0208 *~ 

Ch02/Code09_freq2/Code0209.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0209.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0209
+version:             0.1.0.0
+synopsis:            Using multiset frequency map.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Data
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0209
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7, multiset >=0.2 && <0.3
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code09_freq2/Main.hs

@@ -0,0 +1,10 @@
+import Data.MultiSet (fromList, toOccurList)
+
+data Color = Red | Green | Blue deriving (Show, Ord, Eq)
+
+-- Generates a frequency map using Data.MultiSet
+main :: IO ()
+main = do
+  let items = [Red, Green, Green, Blue, Red, Green, Green]
+  let freq = toOccurList . fromList $ items
+  print freq

Ch02/Code09_freq2/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0209 *~ 

Ch02/Code10_manhattan/Code0210.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0210.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0210
+version:             0.1.0.0
+synopsis:            Calculating the Manhattan distance.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Math
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0210
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7, csv >=0.1 && <0.2
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code10_manhattan/Main.hs

@@ -0,0 +1,22 @@
+import Text.CSV (parseCSV)
+
+-- Computes the Manhattan distance
+main :: IO ()
+main = do
+  let fileName = "input.csv"
+  input <- readFile fileName
+  let csv = parseCSV fileName input
+  let points = either (\e -> []) (map toPoint . myFilter) csv
+  let test1 = [2,1]
+  let test2 = [-10,-10]
+  if (not.null) points then do
+    print $ minimum $ map (manhattanDist test1) points
+    print $ minimum $ map (manhattanDist test2) points
+  else putStrLn "Error: no points to compare"
+  
+toPoint record = map (read :: String -> Float) record
+
+manhattanDist p1 p2 = sum $ zipWith (\x y -> abs (x - y)) p1 p2
+
+myFilter = filter (\x -> length x == 2)
+

Ch02/Code10_manhattan/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0210 *~ 

Ch02/Code10_manhattan/input.csv

@@ -0,0 +1,5 @@
+0,0
+10,0
+0,10
+10,10
+5,5

Ch02/Code11_euclid/Code0211.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0211.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0211
+version:             0.1.0.0
+synopsis:            Computing the Euclidian distance.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Math
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0211
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7, csv >=0.1 && <0.2
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code11_euclid/Main.hs

@@ -0,0 +1,21 @@
+import Text.CSV (parseCSV)
+
+-- Computes the Euclidian distance
+main :: IO ()
+main = do
+  let fileName = "input.csv"
+  input <- readFile fileName
+  let csv = parseCSV fileName input
+  let points = either (\e -> []) (map toPoint . myFilter) csv
+  let test1 = [2,1]
+  let test2 = [-10,-10]
+  if (not.null) points then do
+    print $ minimum $ map (euclidianDist test1) points
+    print $ minimum $ map (euclidianDist test2) points
+  else putStrLn "Error: no points to compare"
+  
+toPoint record = map (\x -> read x :: Float) record
+
+euclidianDist p1 p2 = sqrt $ sum $ zipWith (\x y -> (x - y)^2) p1 p2
+
+myFilter = filter (\x -> length x == 2)

Ch02/Code11_euclid/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0211 *~ 

Ch02/Code11_euclid/input.csv

@@ -0,0 +1,5 @@
+0,0
+10,0
+0,10
+10,10
+5,5

Ch02/Code12_pearson/Code0212.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0212.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0212
+version:             0.1.0.0
+synopsis:            Calculating the Pearson Correlation Coefficient.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Math
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0212
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code12_pearson/Main.hs

@@ -0,0 +1,18 @@
+-- Computes the Pearson coefficient
+main :: IO ()
+main = do
+  let d1 = [3,3,3,4,4,4,5,5,5]
+  let d2 = [1,1,2,2,3,4,4,5,5]
+  let r = pearson d1 d2
+  print r
+  
+pearson xs ys = (n * sumXY - sumX * sumY) / 
+                 sqrt ( (n * sumX2 - sumX*sumX) * 
+                        (n * sumY2 - sumY*sumY) )
+  where n = fromIntegral (length xs)
+        sumX = sum xs
+        sumY = sum ys
+        sumX2 = sum $ zipWith (*) xs xs
+        sumY2 = sum $ zipWith (*) ys ys
+        sumXY = sum $ zipWith (*) xs ys
+

Ch02/Code12_pearson/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0212 *~ 

Ch02/Code13_cos/Code0213.cabal

@@ -0,0 +1,25 @@
+-- Initial Code0213.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Code0213
+version:             0.1.0.0
+synopsis:            Computing cosine similarity.
+-- description:         
+homepage:            haskelldata.com
+license:             GPL-2
+license-file:        ../LICENSE
+author:              Nishant Shukla
+maintainer:          nick722@gmail.com
+-- copyright:           
+category:            Math
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+executable Code0213
+  main-is:             Main.hs
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7
+  -- hs-source-dirs:      
+  default-language:    Haskell2010

Ch02/Code13_cos/Main.hs

@@ -0,0 +1,10 @@
+-- Computes the cosine similarity
+main :: IO ()
+main = do
+  let d1 = [3.5, 2, 0, 4.5, 5, 1.5, 2.5, 2]
+  let d2 = [3, 0, 0, 5, 4, 2.5, 3, 0]
+  let similarity = dot d1 d2 / (eLen d1 * eLen d2)
+  print similarity
+  
+dot a b = sum $ zipWith (*) a b  
+eLen a = sqrt $ dot a a

Ch02/Code13_cos/Makefile

@@ -0,0 +1,5 @@
+default:
+	cabal install --bindir=./
+
+clean:
+	rm -rf dist Setup.hs Code0213 *~ 

Ch02/LICENSE

@@ -0,0 +1,339 @@
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Ch02/README.md

@@ -6,8 +6,22 @@ Refer to the book for step-by-step documentation.
 
 <p align="center"><a href="http://haskelldata.com" target="_blank"><img src="http://haskelldata.com/images/ch02.png"/></a></p>
 
-# How to use
+# Recipes
+* **Code01**: Trimming excess whitespace
+* **Code02**: Ignoring punctuation and specific characters
+* **Code03**: Coping with unexpected or missing input
+* **Code04**: Validating records by matching regular expressions
+* **Code05**: Lexing and parsing an e-mail address
+* **Code06**: Deduplication of nonconflicting data items
+* **Code07**: Deduplication of conflicting data items
+* **Code08**: Implementing a frequency table using Data.List
+* **Code08**: Implementing a frequency table using Data.MultiSet
+* **Code10**: Computing the Manhattan distance
+* **Code11**: Computing the Euclidean distance
+* **Code12**: Comparing scaled data using the Pearson correlation coefficient
+* **Code13**: Comparing sparse data using cosine similarity
 
+# How to use
 ### Setting up the environment
 Install the [Haskell Platform](http://www.haskell.org/platform/).