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-: Welcome back.

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The methods we're gonna talk about

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when it comes to sets are right here.

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It looks like a lot,

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but they're quite similar,

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so hang in there.

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I have two sets for us,

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our my set, which is one through five,

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and then your set, which is four through ten.

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Now let's go one by one

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and see what these methods do.

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And if you've ever seen venn diagrams,

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in your school for example,

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two circles that are overlapping each other,

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what we're about to do is quite similar to this.

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The first one is difference,

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and sets are very useful when having two sets,

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and comparing them to each other.

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So for example, in here,

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difference simply says my set dot difference,

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and we give it another set, such as your set.

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If I print this,

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right here,

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and I click run,

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I get 1, 2, 3.

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It's going to to find the difference

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of the first my set, with your set.

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So any duplicates between the two,

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which is four and five,

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gets ignored, and it only shows the difference.

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That is 1, 2, 3.

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What's different between my set

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and your set, when viewed from my set?

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Well, your set doesn't have 1, 2, 3.

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What about the next one?

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Discard.

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Again, if we do my set dot discard,

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it says it removes an element from a set

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if it is a member.

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So here, we can say discard five,

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and if I do print,

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my set,

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and I click run,

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I get none.

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But if I print here,

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my set,

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and I click run,

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I get 1, 2, 3, 4,

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because we've just discarded five.

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It modifies our set.

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Just to keep our working space clean,

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I'm going to comment these out.

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Next is difference update.

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So I'm going to say, my set,

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and then once again,

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let's see what difference update does.

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Remove all elements of another set from this set.

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So, if I do, your set here,

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and once again, I do print,

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and I click run,

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again, none, because it just modifies my set.

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So remember, we just have to have our print, my set,

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and now, this my set,

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is updated with just one, two and three,

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because we're updating it

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so that the differences are removed.

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So four and five are removed,

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unlike difference,

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where it just told you the difference without changing.

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Again, if we go back here,

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and simply do, my set,

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and I click run,

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you see that, my set here,

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was not modified, right here,

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but then, my set bottom, was modified,

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because of difference update.

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Alright, a few more to go.

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Intersection,

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and this one, once again, my set.

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And in here, once again,

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let's read what it does.

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It just has intersection, with something else.

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Well, let's find out.

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If I do your set here,

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and I do print, and I run this,

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it's going to give me four, five,

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because that's the intersection,

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the two common things,

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that my set and your set has.

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What about isdisjoint?

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Well, if I do my set and then your set,

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I feel like I'm saying those words over and over.

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Hopefully, that's not too annoying.

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And then here, if, let's comment this out.

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We run this, I get false.

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Isdisjoint simply says,

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hey, are those two circles overlapping,

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do they have anything in common?

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If for example,

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my set didn't have four,

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didn't have four and five,

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and I click run, I get true,

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because isdisjointed,

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means these sets have nothing in common.

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Awesome, just a few more.

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The next ones we're gonna see is,

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is issubset,

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and issuperset.

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But actually before we do that,

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let's do union.

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Let's see what this does.

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Union will say my set,

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and in here,

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we want to add the other set, your set.

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If we print this,

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and click run,

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I get 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

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What did that just do?

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Well, union just united these sets together,

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but removed any duplicates.

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That's kind of nice.

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And as you can see,

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it created a new set for us.

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It returned a new set.

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By the way,

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there's actually a shorthand

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that you can do here, in Python,

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which is the shift,

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and then the key above your enter,

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which is right here, this straight line.

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So shift, and then the back slash,

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but if you press shift,

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you'll get this little straight line.

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If you print this,

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remove the brackets here,

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let's run again,

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and you see that works, as well.

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And by the way,

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this also exists for intersection.

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Again, you don't see it that often,

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but with intersection,

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you can do the same thing

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where you just do the end,

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and if you do that,

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it gives you the intersection

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of my set and your set.

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Alright, I promised you this is gonna be short,

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so two other ones, issubset and issuperset.

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As you can imagine, my set,

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if let's say,

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my set only has four and five,

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and I say, hey, is my set, is that a subset,

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of your set?

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And I print this,

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if I click run, it's true.

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My set is a subset that is,

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it's inside of the circle,

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of your set,

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because four and five, is inside of it.

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So my set, the entirety of my set,

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is inside of this other set,

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which we call a subset.

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On the other hand,

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we also have this idea of superset.

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So if I do,

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instead of issubset, issuperset,

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I'll get false,

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because, well, my set,

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is not a superset,

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it doesn't encompass your set,

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it's the other way around.

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Your set is a superset of my set,

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because your set encompasses everything

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that my set has,

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which is four and five.

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Oh boy, that was a lot.

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And you're asking yourself,

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there is no way I'm going to

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memorize any of that.

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Well, good, I don't memorize

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any of this either.

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As a matter of fact, I usually go

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to the Python documentation,

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or just Google around.

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And because I know sets exist,

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if I ever wanna compare,

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let's say two sets, I know to just go here,

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and find the tool that I want.

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That's the key of a programmer

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that I keep mentioning over and over.

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It's not memorization.

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It's the ability to know

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that there's tools that you can use,

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and being able to Google for them.

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I know it doesn't sound exciting,

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because in movies you see everybody typing super fast,

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and coding everything, but that's just not real life.

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In real life,

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you just Google around, find solutions,

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because by now you know what sets are,

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you know what sets can do,

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so that you can Google for methods

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that are appropriate to your problem.

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I'll see you in the next one.

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Bye bye.