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Introduction to Scala

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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.

New Terms:

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.

Further Reading:

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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