How to sort a Scala Map by value

Last Updated : 01 Oct, 2021

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.

How to Sort a list in Scala?

Shivam_k

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How to sort a Scala Map by value

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