DataWeave programming challenge #5: Reverse a phrase's words, but keep the punctuation

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Helpful comments preserved from the original post.

• decipherMiddleware · Aug 16, 2023

  My approach 🤓

  %dw 2.0
  import * from dw::core::Strings
  output application/json
  fun extract(text)=
  do {
      var list= words(text)
      var punc= list map (if(isAlphanumeric($)) "" else $[-1])
      var rev= list[-1 to 0] map ((if(isAlphanumeric($)) $ else $[0 to -2]) ++ punc[$$])
      ---
      rev joinBy(" ")
  }
  
  ---
  payload splitBy("\n") map (line,key)-> extract(line)

• Felix Schnabel · Apr 18, 2023

  My solution:

  %dw 2.0
  output application/json
  import * from dw::core::Strings
  ---
  lines(payload) map (
    words($) map [$, $$] reduce ((cur, acc = words($)[-1 to 0]) ->
    if(!isAlphanumeric(cur[0][-1]))
      acc update {
        case [cur[1]] -> $ ++ cur[0][-1] as String
        case [sizeOf(acc) - cur[1] - 1] -> $[0 to -2]
      }
    else
      acc
    ) joinBy " "
  )

  My first approach was wrong, I just inserted the special chars at the exact index where they were before 😂 So "a, bc" would be "b,c a" what's wrong of course

• Shyam Raj Prasad · Apr 18, 2023

  My approach for this.

  %dw 2.0
  output application/json
  import * from dw::core::Strings
  ---
  /* Expected output:
  [
    "world Hello",
    "you with be Fourth the May",
    "world Hello!",
    "Fourth the, May be you With",
    "Fourth the, May be you With!"
  ]
  */
  (payload splitBy  "\n") map (
    do {
        var  y = $ splitBy  " " map ($ filter isAlphanumeric($))
        var x =($ splitBy " ") map if(isAlphanumeric($)) "" else $ filter !(isAlphanumeric($))
    ---
    y [-1 to 0] map (
      $ ++ x[$$] 
     ) joinBy  " "
    }
  )

• ↳ Reply to Shyam Raj Prasad

  Alex Martinez · Apr 18, 2023

  OH MY GOD SO EASY!!! Love it!!!

• ↳ Reply to Shyam Raj Prasad

  Felix Schnabel · Apr 18, 2023

  Damn, that solution is so nice. I was kinda thinking in that direction but couldn't write it down

FAQs

Frequently asked questions about this post.

• What does this DataWeave challenge ask you to do?

  You write a DataWeave script that reverses the order of the words in each phrase to form a new phrase, where phrases are separated by a new line and words are separated by a space, but the punctuation signs (! and ,) stay in the same place; for example "Hello world!" becomes "world Hello!" and "With you, be May the Fourth!" becomes "Fourth the, May be you With!". Lower and upper cases can be kept as-is.

• How should the punctuation be handled when reversing the words?

  The punctuation signs stay in the same place rather than moving with the words, so as Clue #1 suggests you keep the index of each punctuation sign so you can insert it back there later after the words have been reversed.

• What clues does the post give if I get stuck?

  The post offers four clues: first, keep the index of each punctuation sign so you can insert it there later; second, you can use the isAlphanumeric function from the Strings module; third, you can use the scan function to separate each phrase into an Array of Strings; and finally you can use the joinBy function to transform from Array to String.

• Can I output the result as text instead of JSON?

  Yes, the post notes you can keep the output as a JSON or as a text, whatever your preference is.

• Where can I try solving this challenge?

  You can solve it on the DataWeave Playground using the linked project at https://dataweave.mulesoft.com/learn/playground?projectMethod=GHRepo&repo=alexandramartinez%2Fdataweave-challenges&path=challenges%2F5 , and the post recommends referring only to the DataWeave documentation at https://docs.mulesoft.com/dataweave/latest/ rather than Google or others so you can learn on your own.

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