How to sort a Scala Map by value

In this article, we will learn how to sort a Scala Map by value. We can sort the map by key, from low to high or high to low, using sortBy method. 

Syntax:

MapName.toSeq.sortBy(_._2):_*

Let’s try to understand it with better example. 

Example #1:

Scala

// Scala program to sort given map by value
import scala.collection.immutable.ListMap

// Creating object
object GfG
{

    // Main method
    def main(args:Array[String])
    {

        // Creating a map
        val mapIm = Map("Zash" -> 30,
                        "Jhavesh" -> 20,
                        "Charlie" -> 50)


        // Sort the map by value
        val res = ListMap(mapIm.toSeq.sortBy(_._2):_*)
        println(res)
    }
}

Output:

Map(Jhavesh -> 20, Zash -> 30, Charlie -> 50)

In above example, we can see mapIm.toSeq.sortBy method is used to sort the map by key values.

Example #2: 

Scala

// Scala program to sort given map by value
// in ascending order
import scala.collection.immutable.ListMap

// Creating object
object GfG
{

    // Main method
    def main(args:Array[String])
    {

        // Creating a map
        val mapIm = Map("Zash" -> 30,
                        "Jhavesh" -> 20,
                        "Charlie" -> 50)

        // Sort map value in ascending order
        val res = ListMap(mapIm.toSeq.sortWith(_._2 < _._2):_*)
        println(res)
    }
}

Output:

Map(Jhavesh -> 20, Zash -> 30, Charlie -> 50)

Here, In above example we are sorting map in ascending order by using mapIm.toSeq.sortWith(_._2 < _._2):_* 

Example #3: 

Scala

// Scala program to sort given map by value
// in descending order
import scala.collection.immutable.ListMap

// Creating object
object GfG
{

    // Main method
    def main(args:Array[String])
    {

        // Creating a map
        val mapIm = Map("Zash" -> 30,
                        "Jhavesh" -> 20,
                        "Charlie" -> 50)

        // Sort map value in descending order
        val res = ListMap(mapIm.toSeq.sortWith(_._2 > _._2):_*)
        println(res)
    }
}

Output:

Map(Charlie -> 50, Zash -> 30, Jhavesh -> 20)

Above example show to sorting map in descending order.