Scala Tutorial - Learn How To Use SortBy Function With Examples

By Nadim Bahadoor | Last updated: December 11, 2017 at 21:09 pm

Overview

In this tutorial, we will learn how to use the sortBy function with examples on collection data structures in Scala. The sortBy function is applicable to both Scala's Mutable and Immutable collection data structures.

 

The sortBy method takes a predicate function and will use it to sort the elements in the collection.

 

As per the Scala documentation, the definition of the sortBy method is as follows:

def sortBy[B](f: (A) ⇒ B)(implicit ord: math.Ordering[B]): Repr

The sortBy method is a member of SeqLike trait.

Steps

1. How to create a case class to represent Donut objects

In the Learn how to define and use case class tutorial, we showed how to represent objects in Scala using case classes. Similarly, in the code below, we will use a case class to represent an object of type Donut.


println("\nStep 1: How to create a case class to represent Donut objects")
case class Donut(name: String, price: Double)

 

2. How to create a Sequence of type Donut

Using the Donut case class from Step 1, the code below shows how to create a Sequence of type donuts.


println("\nStep 2: How to create a Sequence of type Donut")
val donuts: Seq[Donut] = Seq(Donut("Plain Donut", 1.5), Donut("Strawberry Donut", 2.0), Donut("Glazed Donut", 2.5))
println(s"Elements of donuts = $donuts")

You should see the following output when you run your Scala application in IntelliJ:


Step 2: How to create a Sequence of type Donut
Elements of donuts = List(Donut(Plain Donut,1.5), Donut(Strawberry Donut,2.0), Donut(Glazed Donut,2.5))

 

3. How to sort a sequence of case class objects using the sortBy function

The code below shows how to use the sortBy method to sort the Sequence of type donuts from Step 2. Note that we will sort each donut element by using its price property.


println("\nStep 3: How to sort a sequence of case class objects using the sortBy function")
println(s"Sort a sequence of case class objects of type Donut, sorted by price = ${donuts.sortBy(donut => donut.price)}")

You should see the following output when you run your Scala application in IntelliJ:


Step 3: How to sort a sequence of case class objects using the sortBy function
Sort a sequence of case class objects of type Donut, sorted by price = List(Donut(Plain Donut,1.5), Donut(Strawberry Donut,2.0), Donut(Glazed Donut,2.5))

This concludes our tutorial on Learn How To Use SortBy Function With Examples and I hope you've found it useful!

 

Stay in touch via Facebook and Twitter for upcoming tutorials!

 

Don't forget to like and share this page :)

Summary

In this tutorial, we went over the following:

  • How to create a case class to represent Donut objects
  • How to create a Sequence of type Donut
  • How to sort a sequence of case class objects using the sortBy function

Tip

  • Review the tutorials on Mutable and Immutable collection data structures in Scala.

Source Code

The source code is available on the allaboutscala GitHub repository.

 

What's Next

In the next tutorial, I will show you how to use the sorted function.

Nadim Bahadoor on FacebookNadim Bahadoor on GithubNadim Bahadoor on LinkedinNadim Bahadoor on Twitter
Nadim Bahadoor
Senior Principal Engineer | Elsevier
Founder of allaboutscala.com. I have over 10 years of experience in building large scale real-time trading systems in the financial industry. Passionate about Distributed Systems, Scala, Big Data and Functional Programming. Stay in touch for upcoming tutorials!
Other allaboutscala.com tutorials you may like:

Share this article on