31 Working with List: filtering

 

After reading this lesson, you will be able to:

  • Remove or select items from a sequence based on their position
  • Filter elements of a list that respect a given predicate
  • Remove duplicated items in a sequence

In the previous lesson, you have learned how to select a single element in a sequence based on its position or features. In this lesson, you’ll continue to discover other operations you can perform on an instance of List. You’ll see how to create a new list from an existing one by selecting one of its subsections. You’ll discover how to pick elements that have specific characteristics. Finally, you’ll learn how to create a new sequence that contains no duplicated items. In the capstone, you’ll use these operations to create a subset of movies that have specific characters.

Consider this

Suppose you need to define a function to select all the even numbers in a given sequence of integers. How would you implement it? 

31.1  Dropping and Taking elements

In the previous lessons, you have been developing a program to store your contacts. Let’s recall that your program represents a contact record as following:

31.2  Filtering Items of a List

31.3  Removing duplicates

31.4  Summary

31.5  Answers to Quick Checks