32 Working with List: Sorting and other operations

 

After reading this lesson, you will be able to

  • Sort a list
  • Produce a string representation of a sequence
  • Sum all the numerical elements of a list
  • Group items according to given criteria

In the previous lesson, you mastered how to filter elements of a sequence. In this lesson, you’ll learn about a variety of operations you can perform on lists. You’ll discover different approaches to sorting the items of a sequence. Also, you’ll learn how to produce a text representation for it. Finally, you’ll see how to restructure your list into a dictionary-like structure that groups elements with common features. In the capstone, you’ll use these operations to rank the films in the movies data set and display your data analysis in a human-readable form.

Consider this

Imagine you have a numerical list, and you’d like to sort its elements from its largest number to its smallest one. How would you implement it?

32.1 Sorting elements

In this unit, you have developed a software program to manage an address book to represent each contact.

Listing 32.1 Representing a contact
case class Contact(name: String,
                   surname: String,
                   numbers: List[ContactNumber],
                   company: Option[String],
                   email: Option[String])
 
sealed trait Label
case object Work extends Label
case object Home extends Label
 
case class ContactNumber(number: String, label: Label)

32.2 Converting a list to a string

32.3 Sum elements of numerical sequences

32.4 Grouping elements by feature

Summary

Answers to quick checks