Kotlin to use groupby multiple fields and adding values

I am trying to calculate the total costs by grouping multiple items using Kotlin’s built in method

I have a data structure like following;

Data(id=1, cost=1, env='prod', item='Storage')
Data(id=2, cost=2, env='qa', item='Storage')
Data(id=3, cost=3, env='prod', item='Storage')

Data(id=4, cost=5, env='qa', item='Bandwidth')
Data(id=5, cost=2, env='qa', item='Bandwidth')
Data(id=6, cost=5, env='prod', item='Bandwidth')
Data(id=7, cost=6, env='prod', item='Bandwidth')
Data(id=8, cost=1, env='prod', item='Bandwidth')

Data(id=9, cost=5, env='qa', item='vm')
Data(id=10, cost=2, env='uat', item='vm')
Data(id=11, cost=3, env='qa', item='vm')
Data(id=12, cost=4, env='prod', item='vm')
Data(id=13, cost=5, env='uat', item='vm')

I would like to add the cost using "item" and "env"

So expected end result will be

data class TotalCost(val item: String, val env: String, val cost: Double){}


{
    ("Storage", "prod", 4)
    ("Storage", "qa", 2)
    
    ("Bandwidth", "qa", 7)
    ("Bandwith", "prod", 12)
    
    ("vm","qa", 8)
    ("vm", "uat", 7
    ("vm", "prod", 4)
}

I tried using groupBy but couldn’t get the result i want.

>Solution :

data class Data(
  val id: Int,
  val cost: Int,
  val env: String,
  val item: String
)

data class TotalCost(
  val item: String,
  val env: String,
  val cost: Double
)

val input = listOf(
  Data(id = 1, cost = 1, env = "prod", item = "Storage"),
  Data(id = 2, cost = 2, env = "qa", item = "Storage"),
  Data(id = 3, cost = 3, env = "prod", item = "Storage"),

  Data(id = 4, cost = 5, env = "qa", item = "Bandwidth"),
  Data(id = 5, cost = 2, env = "qa", item = "Bandwidth"),
  Data(id = 6, cost = 5, env = "prod", item = "Bandwidth"),
  Data(id = 7, cost = 6, env = "prod", item = "Bandwidth"),
  Data(id = 8, cost = 1, env = "prod", item = "Bandwidth"),

  Data(id = 9, cost = 5, env = "qa", item = "vm"),
  Data(id = 10, cost = 2, env = "uat", item = "vm"),
  Data(id = 11, cost = 3, env = "qa", item = "vm"),
  Data(id = 12, cost = 4, env = "prod", item = "vm"),
  Data(id = 13, cost = 5, env = "uat", item = "vm")
)

val result = input
  .groupBy { 
    it.item to it.env 
  }
  .map { (key, value) ->
    listOf(
      key.first,
      key.second,
      value.sumOf { it.cost }
    )
  }

result.forEach(::println)

Output:

[Storage, prod, 4]
[Storage, qa, 2]
[Bandwidth, qa, 7]
[Bandwidth, prod, 12]
[vm, qa, 8]
[vm, uat, 7]
[vm, prod, 4]