Dataweave Series for Practice & Interview Part-7

Practice Dataweave here :- Dataweave Playground

Important Note:- First Copy Input, Output, DW Code & Use Json Online Validator, to format the JSON, since medium changes the JSON.

1. Given a list of numbers, write a function to find the first number that appears more than once

Input:-

[1,2,3,1,2]

Output:-

1

Dataweave Code:-

%dw 2.0
output application/json
var seen = []
fun findFirstDuplicate(numbers,seen=[]) =
numbers map ((item, index) ->
    if (seen contains (item) ~= true)
    log(findFirstDuplicate(numbers[1 to -1],(seen + item)))
    else log(item)
)
---
findFirstDuplicate(payload,seen)

2. Given a list of words, write a function to find the longest palindromic substring

Input:-

Output:-

Dataweave Code:-

3. Given a Number, Find its Factorial

Input:-

6

Output:-

720

Dataweave Code:-

%dw 2.0
output application/json
fun Factorial(n:Number, prod:Number=1) =
(if (n==1 or n==0) prod 
else Factorial(n-1,(prod*n))) 
---
Factorial(payload)

4. Sum of Digits of a Number till its a single digit. (E.g:- 789 -> 7+8+9 = 24 | 2+4 = 6)

Input:-

789

Output:-

6

Dataweave Code:-

%dw 2.0
import lines from dw::core::Strings
output application/json
fun sumOfDigits(num, result=0) = 
do {
var new = (num reduce $+$$) as String
---
if (sizeOf(new) > 1) sumOfDigits(new, result+new)
else new
}
---
sumOfDigits(sum(lines(payload))) as Number

5.

Input 1:-

[
  {
    "fName": "Max",
    "lName": "Mule"
  },
  {
    "fName": "John",
    "lName": "Paul"
  },
  {
    "fName": "balu",
    "lName": "Paul"
  },
  {
    "fName": "Max",
    "lName": "Paul"
  },
  {
    "fName": "piki",
    "lName": "Paul"
  }
]

Input 2:-

var a = ["Max", "balu"]

Output:-

[
  {
    "fName": "Max",
    "lName": "Mule"
  },
  {
    "fName": "Max",
    "lName": "Paul"
  }
]

Dataweave Code:-

%dw 2.0
output application/json
var a = ["Max", "balu"]
---
payload map ((item, index) -> 
{
    "fname":(a filter($==item.fName))[0],
    "lname":item.lName
}
)filter ((item, index) -> !(item.fname==null)) distinctBy $.fname

6.

Input:-

[1,3,2,2,5,5,5,4]

Output:-

[
  {
    "duplicates": "Number is: 2 size is 2"
  },
  {
    "duplicates": "Number is: 5 size is 3"
  }
]

Dataweave Code:-

%dw 2.0
output application/json
---
(((payload groupBy $) pluck $) map (value) -> {
    (duplicates: "Number is: " ++ value[0] ++ " size is " ++  sizeOf(value)) if sizeOf(value) > 1
}) filter ($ != {})

📢 Check the other Articles in the Dataweave Series:- Dataweave Series for Practice & Interview Part 1–10

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