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This topic is about Scala Collections – Reduce Method.

reduce() method is a member of TraversableOnce trait, it is used to collapse elements of collections. It is similar to fold method but it does not take initial value.

Syntax

The following is the syntax of reduce method.

def reduce[A1 >: A](op: (A1, A1) ? A1): A1

Here, reduce method takes associative binary operator function as a parameter. This method returns the resultant value.

Usage

Below is an example program of showing how to use fold method −

Example

object Demo {
   def main(args: Array[String]) = {
      val list = List(1, 2, 3 ,4)
      //apply operation to get sum of all elements of the list
      val result = list.reduce(_ + _)
      //print result
      println(result)      
   }
}

Save the above program in Demo.scala. The following commands are used to compile and execute this program.

Command

\>scalac Demo.scala
\>scala Demo

Output

10

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