Sets are another type of data structure that do not preserve order. 0:00 Unlike tuples, sets do not allow duplicates. 0:04 Each element's order is determined by the value returned from the hash code method. 0:08 Sets are immutable by default. 0:12 Let's start by cleaning up some of our previous code associated to maps 0:15 and tuples. 0:19 Awesome, let's create a set of integers from one to five. 0:23 In this example, we insert each value in the set in increasing order. 0:32 However, if we print out the values of the set, 0:37 the first thing we'll notice is that the order is not preserved. 0:40 Let's take a look. 0:44 Let's recompile and check out our results. 0:50 If we really want to maintain the order that each element was inserted in the set, 0:54 we can use a LinkedHashSet, which implements a linked list under the hood. 1:00 To do so, we will need to import the scala.collection.mutable LinkedHashSet. 1:04 Let's do so at the top of our file and create a new LinkedHashSet. 1:10 Awesome, let's recompile our app and check out our results. 1:48 Perfect, we've created an orderedSet that maintains the order of our elements. 1:52 In order to create a mutable set, 1:57 we need to import the scala.collection.mutable set. 1:59 Let's do so at the top of our file and create a new mutable set. 2:03 Similarly to other collections to add or remove elements from a set, 2:27 we would simply use the plus equal or minus equal methods. 2:31 Let's take a look. 2:36 Great, let's recompile and check out our results. 2:48 Awesome, as expected, we were able to remove the number 5 from our set, and 2:53 we're also able to add the number 4. 2:58 We can achieve some very useful functionality with sets, and 3:00 that's by using the methods intersect and union. 3:04 Intersect grabs the values which are contained in both sets, 3:07 while union adds each unique value in both sets. 3:12 Let's take a look at how those work. 3:17 Awesome, as we can see, we have a set for 3:53 the unionResult and a set for the intersectResult. 3:56 Let's dissect the intersectResult. 3:59 Remember, intersect just means that we grab the values that are contained in both 4:02 sets and here, we get the number 4. 4:06 That's because both sets, nums as well as numbers, both contain the number 4. 4:10 Great, we've gone through quite a few collections in Scala, and 4:16 we've learned a lot about Scala's mutable and immutable data structures. 4:19 In the next videos, we'll learn about high order functions in Scala, and 4:24 how to apply some of those functions to Scala collections. 4:28