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Sets

4:32 with andi mitre

Sets are another type of data structure that do not preserve order. Unlike tuples, sets do NOT allow duplicates.

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Sets -- A set is another data structure which does not contain any duplicates nor preserves order. Each element in a set gets its order from the return value of the hashCode function.

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Sets
Set documentation & methods

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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

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