June 2018 Update

Task/Natural-sorting/Haskell/natural-sorting.hs

@@ -0,0 +1,89 @@
+import Data.List
+import Data.Char
+import Data.String.Utils
+import Data.List.Utils
+import Data.Function (on)
+
+
+printOutput = do
+                putStrLn "# Ignoring leading spaces \n"
+                printBlockOfMessages sample1Rule ignoringStartEndSpaces
+                putStrLn "\n # Ignoring multiple adjacent spaces (m.a.s) \n"
+                printBlockOfMessages sample2Rule ignoringMultipleAdjacentSpaces
+                putStrLn "\n # Equivalent whitespace characters \n"
+                printBlockOfMessages sample3Rule ignoringMultipleAdjacentSpaces
+                putStrLn "\n # Case Indepenent sorts \n"
+                printBlockOfMessages sample4Rule caseIndependent
+                putStrLn "\n # Numeric fields as numerics \n"
+                printBlockOfMessages sample5Rule numericFieldsAsNumbers
+                putStrLn "\n # Title sorts \n"
+                printBlockOfMessages sample6Rule removeLeadCommonWords
+
+printMessage message content = do
+                 putStrLn message
+                 mapM_ print content
+
+printBlockOfMessages list function = do
+      printMessage "Text strings:" list
+      printMessage "Normally sorted:" (sort list)
+      printMessage "Naturally sorted:" (sortListWith list function)
+
+
+-- samples
+sample1Rule = ["ignore leading spaces: 2-2", " ignore leading spaces: 2-1", "  ignore leading spaces: 2+0",  "   ignore leading spaces: 2+1"]
+sample2Rule = ["ignore m.a.s spaces: 2-2", "ignore m.a.s  spaces: 2-1", "ignore m.a.s   spaces: 2+0", "ignore m.a.s    spaces: 2+1"]
+sample3Rule = ["Equiv. spaces: 3-3", "Equiv.\rspaces: 3-2", "Equiv.\x0cspaces: 3-1", "Equiv.\x0bspaces: 3+0", "Equiv.\nspaces: 3+1", "Equiv.\tspaces: 3+2"]
+sample4Rule = ["cASE INDEPENENT: 3-2", "caSE INDEPENENT: 3-1", "casE INDEPENENT: 3+0", "case INDEPENENT: 3+1"]
+sample5Rule = ["foo100bar99baz0.txt", "foo100bar10baz0.txt", "foo1000bar99baz10.txt", "foo1000bar99baz9.txt"]
+sample6Rule = ["The Wind in the Willows", "The 40th step more", "The 39 steps", "Wanda"]
+
+
+-- function to execute all sorts
+sortListWith l f = sort $ f l
+
+-- 1. Ignore leading, trailing and multiple adjacent spaces
+
+ -- Ignoring leading spaces
+
+-- receive a String and remove all spaces from the start and end of that String, a String is considered an List os Char
+-- ex: "  a string " = "a string"
+ignoringStartEndSpaces :: [String] -> [String]
+ignoringStartEndSpaces = map strip
+
+-- Ignoring multiple adjacent spaces and Equivalent whitespace characters
+
+ignoringMultipleAdjacentSpaces :: [String] -> [String]
+ignoringMultipleAdjacentSpaces = map (unwords . words)
+
+-- 2. Equivalent whitespace characters
+-- 3. Case independent sort
+-- lower case of an entire String
+-- ex "SomeCAse" = "somecase"
+caseIndependent :: [String] -> [String]
+caseIndependent = map (map toLower)
+
+-- 4. Numeric fields as numerics (deals with up to 20 digits)
+numericFieldsAsNumbers :: [String] -> [[Int]]
+numericFieldsAsNumbers = map findOnlyNumerics
+
+findOnlyNumerics :: String -> [Int]
+findOnlyNumerics s = convertDigitAsStringToInt $ makeListOfDigitsAsString $ extractDigitsAsString s
+extractDigitsAsString :: String -> [String]
+extractDigitsAsString s = map (filter isNumber) $ groupBy ((==) `on` isNumber ) s
+makeListOfDigitsAsString :: [String] -> [String]
+makeListOfDigitsAsString l = tail $ nub l
+convertDigitAsStringToInt :: [String] -> [Int]
+convertDigitAsStringToInt = map (joiner . map  digitToInt)
+
+-- join a list of numbers into a single number
+-- ex [4,2] = 42
+joiner :: [Int] -> Int
+joiner = read . concatMap show
+
+-- 5. Title sort
+removeLeadCommonWords l = map removeLeadCommonWord $ splitList l
+
+splitList = map words
+removeLeadCommonWord a = unwords $ if f a commonWords then tail a else a
+                        where f l1 = elem (map toLower (head l1))
+                              commonWords = ["the","a","an","of"]