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All right, let's learn about some actions that we can take on lists, and this is very exciting because

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you can perform a lot of actions on lists.

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Now, we've learned about in functions, right.

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Functions that come with Python.

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And we've actually seen this one before when we talked about strength's, which is the length function,

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and here we can have it calculate the length of a list.

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So, for example, if we had a basket here that had one, two, three, four, five.

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Well, this basket, if I calculate the length of the basket, let's do print here so we can see the

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result.

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And I click run.

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The length of the basket is five, because while there's five items, remember, a length is the actual

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length, it doesn't start counting from zero.

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It's going to do human length, which is five.

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But lists get really powerful when it comes to methods, so instead of a built in function, remember

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a method is a faction that it's owned by something and is specific, let's say, to a data type.

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So if we go to list methods, you'll see that Python has a few less methods that we can use.

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And the way we use.

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These methods is, remember, we just add a dot.

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After a list.

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So let's have a look at some of them first, I'm going to start off with the adding ons, so let's say

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in this basket we want to add something to it to the end of the list.

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Well, we can use the append.

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And remember, with a method, as soon as you write the dot, I'll tell you what we can use, which

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is very, very useful when you have an editor.

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So the first one is a pen.

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And if I hover over this, well, it just tells me appends an object to end.

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And in Python, an object is well, everything in Python is an object.

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A number is an object.

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A list is an object.

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So just think of it as an item for now, so if I want to spend, let's say, one hundred to the end

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of the list and you know what?

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Let's add a new list here.

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And this new list will do the append for us if I print the new list and I click run.

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I get none.

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Hmm, that's weird.

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What if I print?

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Basket here.

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If I click, run.

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All right, so it looks like.

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The basket was a Pennetta, we added a hundred, but a new list when we assigned it the basket append

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that new list is completely none and that is because append changes the list in place.

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What does in place mean?

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It means that it doesn't produce a value.

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All it does is saying, hey, I'm just going to append a hundred to this basket that you gave me, but

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I don't really care.

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I'm not producing a result.

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I'm just changing this for you.

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I know it's a little confusing, so in order for our new list to have that one hundred at the end,

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we have to do something like this.

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There we go after we've appended.

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To the basket, then we can assign so that new list points to Basket, which points to this list that

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was modified.

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All right, what else is there?

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Well, there's also something called insert, and you see over here that insert gives an index and an

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object so we can insert something not at the end of the list.

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I mean, we could but we can also insert it anywhere we want in an index.

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So, for example, in this case, if I do insert a 100.

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At zero one, two, three, four, celesta index of four and I click run!

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I've added 100 to the index of four, if I do index of five and I click run.

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I've added one hundred at the end of the list.

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Now let's try and copy this and see if we can just add it into here.

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If I click, run.

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Again, same thing Insert modifies the list in place, it doesn't create a new copy of the list.

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All right, and if we add this.

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Like this.

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Once again, Insert modifies the list in place, that is, it doesn't really output a new list, it

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just modifies whatever is existing in memory.

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Finally, there is another method called extend and extend instead of an actual item or object takes

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what we call an iterable, which we're going to get into later on.

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But it's something that you can loop over.

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You can iterate over, which is a list.

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So we just give it another list, like, let's say one hundred or one hundred and one.

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So if I run this once again, it doesn't I'll put a new list, it just modifies the list in place and

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adds on.

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Or extends our list and we can also just give it one item.

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All right, let's keep going with the removing method's.

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Now, with the removing, we once again have a few fun things that we can do.

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So let's continue with this basket that we've been using that now has one hundred included into it.

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And the way we can remove things is, well, there's a few ways.

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First one is basket, dot, pop and basket up pop.

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If I go like this and let's print this basket, I'm going to comment about the new list for now, since

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we're not using it and then we're going to say basket, dot, pop and then print.

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Let's run this.

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And Pop pops off whatever is at the end of the list, in our case, at the end of the list, because

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we've extended the basket to one hundred, that one hundred gets removed.

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If I do BASKETT pop again.

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Hope not here, down here and I run.

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You see that both a hundred and five get removed.

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What if I do pop zero?

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If I click run here.

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It removes the item.

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In the index, so here, Pop Zero is going to remove whatever is an index of zero, which is one.

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Now there's also dot remove.

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Remove again is we give it a value that we want to remove.

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So in our case, let's say we want to remove number four.

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Well, if we run this.

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It's going to remove four for us, so remove we give it the value that we want to remove with pop,

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we give it the index that we want to remove.

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And just to see if this is working, let's add a new list here.

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And we'll say new list equals Baskette remove.

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Add a new list here, see if that gets modified.

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No, it does not get modified, that means remove is working in place, it doesn't return a value.

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It just simply changes whatever list you give it.

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What if we do, Pop?

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If I run this, I get five, hmmm, why is that?

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And this is something that you just have to get used to different methods, do different things.

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For example, pop, the way it works is that pop returns, whatever you have just removed in our case

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when we did for that is index of zero one, two, three, four eight.

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Return the number five for me.

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Even though it removed it from the basket, it's still returned something and the reason for others

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is that we got none.

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That is when a method doesn't return anything, it returns none.

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A topic we're going to cover shortly.

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So you have to be careful and understand what each method returns.

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If I go overextend, I see here that this little arrow shows me that none is returned.

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That means it's not going to produce anything with this method.

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It's only going to change or extend a list that it was given.

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Don't worry if this is confusing, that's something that you're going to get used to as we get more

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and more practice.

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Now, the last removing method I want to show you is clear and clear, as you might guess.

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Fight, click, run here.

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Well, this is none, but if I go to the basket and I click Run!

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The basket is empty, clear, removes whatever is in the list, completely clears it.

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Just as the name suggests.

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All right, that was a lot, but there's still a few more, so let's take a break and I'll see you in

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the next video.

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Bye bye.