Count Words In File, And Find Words That Are Anagrams Assignment Solution

Instructions

Objective

Write a haskell assignment program to count words in file, and find words that are anagrams.

Requirements and Specifications

Counting Words

In this assignment you will produce a sorted word count from input text. The input will be a text stream as in the rot13 program and you will output a list of words with their associated counts such that the words are sorted (String is in typeclass Ord and so that ordering is acceptable) and all in lower-case. E.g. the text:

A parser for things Is a function from strings To lists of pairs Of things and strings should output:

• a 2
• and 1
• for 1
• from 1
• function 1
• is 1
• lists 1
• of 2
• pairs 1
• parser 1
• strings 2
• things 2
• to 1

Implement this as a program with the exact name WordCount.hs such that it can be run as ./WordCount like the rot13 program. It should be in the assignment4 directory of your repository.

A word is defined as a contiguous sequence of letters with the quote character '\'' and the dash character '-'. That means "dog's" and "about-face" are each considered one word. Note that '\'':[] == "'".

Screenshots of output

Source Code

Word count

module Main where import Data.Char import Data.List import qualified Data.Map.Strict as Map -- Get a map with all the words found and the counts for each one getWordCounts :: String -> Map.Map String Int getWordCounts xs = getFreqs (map toLower xs) [] where getFreqs [] [] = Map.empty getFreqs [] ys = Map.singleton ys 1 getFreqs (x:xs) ys = if (not (isAlpha x)) && x /= '\'' && x /= '-' then if null ys then getFreqs xs [] else Map.unionsWith (+) [Map.singleton ys 1, getFreqs xs []] else getFreqs xs (ys ++ [x]) -- Gets an input string and returns the text showing the word counts getWordCountsStr :: String -> String getWordCountsStr xs = (intercalate "\n" (map entryToStr (Map.toAscList (getWordCounts xs)))) ++ "\n" where --converts a map entry to a string "k v" entryToStr (xs,n) = xs ++ " " ++ (show n) main :: IO () main = interact getWordCountsStr

Collector permutation

module Main where import Data.Char import Data.List import qualified Data.Map.Strict as Map import Control.Category -- Get a map with all the words found and the counts for each one getWordCounts :: String -> Map.Map String Int getWordCounts xs = getFreqs (map toLower xs) [] where getFreqs [] [] = Map.empty getFreqs [] ys = Map.singleton ys 1 getFreqs (x:xs) ys = if (not (isAlpha x)) && x /= '\'' && x /= '-' then if null ys then getFreqs xs [] else Map.unionsWith (+) [Map.singleton ys 1, getFreqs xs []] else getFreqs xs (ys ++ [x]) -- Determines is a pair of strings are permutations of each other isPermutation :: String -> String -> Bool isPermutation [] [] = True isPermutation _ [] = False isPermutation [] _ = False isPermutation (x:xs) ys = case span (/= x) ys of (hs, []) -> False (hs, ts) -> isPermutation xs (hs ++ (tail ts)) -- Makes groups of permutations for a given list of words with same lengths groupPermutations :: [String] -> [[String]] groupPermutations [] = [] groupPermutations [_] = [] -- ignore single permutations groupPermutations (x:xs) = case partition (isPermutation x) (x:xs) of -- get all permutations ([_],zs) -> groupPermutations zs -- no permutations of x (ys, zs) -> ys : (groupPermutations zs) collectPermutations :: String -> String collectPermutations xs = getWordCounts >>> Map.keys >>> -- get the list of words filter lenGT1 >>> -- remove single letter words sortOn length >>> -- sort by length (groupBy eqLen) >>> -- group by same lengths (filter lenGT1) >>> -- remove lists that have only one word (foldr (\x y -> (groupPermutations x) ++ y) []) >>> -- group by permutations and flatten list (map listToStr) >>> -- Convert each sublist to a string line sort >>> -- sort line strings intercalate "\n" >>> -- separate lines by newlines (++ "\n") $ xs -- append ending newline where eqLen xs ys = length xs == length ys lenGT1 xs = length xs > 1 listToStr xs = intercalate ", " xs main :: IO () main = interact collectPermutations