Group the strings with occurrence count from a List using scala

Sudarshan Kasar

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Feb 14, 2024

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package exercise

import scala.collection.mutable

object UniqueElementsWithCount extends App {
  /*
  input - List(Student("abc"), Student("def"), Student("abc"))
  case class Student(name: String)
  o/p  : Map("abc" -> 2, "def" -> 1)
  */
  case class Student(name: String)

  val list: List[Student] = List(Student("abc"), Student("def"), Student("abc"))


  import scala.collection.mutable.Map
  val counter = (students: Map[String, Int], student: Student) => if (students.contains(student.name)) {
    val ss = students(student.name)
    students += (student.name -> (ss + 1))
  } else students += (student.name -> 1)

  val studentsWithCount: mutable.Map[String, Int] = list.foldLeft(Map.empty[String, Int]) { (students, student) =>
    if(students.contains(student.name)) {
      val ss = students(student.name)
      students += (student.name -> (ss + 1))
    } else students += (student.name -> 1)
  }
  studentsWithCount map println
  
  //clean code with functions
  val studentsCountWithFunction = list.foldLeft(Map.empty[String, Int])(counter)
  studentsCountWithFunction map println

}