how to sum only the max value for common prefix inside the array in scala-CodePudding

I have array contain string items in scala , each item contain from prefix || double value like below :

var y = Array("Zara||6.0", "Nuha||4.0","Zara||2.0","Zara||0.1")

what I want to Do :

i need sum all double value from above array (y(i).split("\|\|")(1)) But if the prefix the duplicated in the array then I only want sum the max value like below : for item Zara we have 3 values i want to take the max (in our sample it 6.0) for item Nuha it unique then i will take it's value (4.0)

the excepted output is (6.0 4.0)=10.0

is there are any way to do it in scala rather than using 2 instead loop ?

CodePudding user response：

Prepare your array: extract prefix and values into tuple. Use foldLeft for aggregate max elem for each prefix, and sum values

val res = y.map(_.split("\\|\\|")).map(arr => (arr(0), arr(1).toDouble))
      .foldLeft(Map.empty[String, Double]) { (acc, elem) =>
        val value = acc.get(elem._1).map(math.max(_, elem._2)).getOrElse(elem._2)
        acc   (elem._1 -> value)
      }.values.sum
     
println(res)