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Often you will want to start with an existing list and make an entirely new list based on the first

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one.

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So let's explore how copying a list works and examine one situation in which copying a list is useful.

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So to copy a list, you can make a slice that includes the entire original list by omitting the first

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index and the second index like this.

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Right.

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So this tells Python to make a slice that starts at the first item and ends with the last item producing

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a copy of the entire list.

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For example, imagine we have a list of four list of our favorite car makers and want to make a separate

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list of car makers that our friend drives.

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So this friend likes everything in our list and drives everything on our list so far so we can create

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their list by copying ours.

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So in order to do that, you will write friend's friend that.

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Friend that.

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Likes cars.

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And here we will use this and let's actually my.

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My favorite.

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Custom cars.

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And here.

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Friends.

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And here.

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Now we will use this.

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My favorite cars.

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And this.

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And after that we will.

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Uh, firstly.

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Prentiss Brown's favorite cars and after that.

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So firstly, of course, this is the friend favorite cars and this is my favorite cars.

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And after that we first we will first print the my favorite cars.

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So print.

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My favorite.

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Cars are like this.

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And after that we will print our my favourite cars.

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And after that we will print.

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Of course we need to add new line before it.

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So my friends.

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Favorite cars are here.

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And after that we will print.

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Friends.

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Friends.

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Favorite cars.

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And here we will run this now.

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And as you can see, this is our output.

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So I added this new line here.

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Oops, sorry again.

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It's not working or.

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Yes, it's working now.

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Okay.

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So here I added this new line character to this to show our output.

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New line here.

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So I could we added this new line after the.

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My favorite cars here, but it's more easy to add here.

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Instead of writing some formatting and things in last my favorite cars print function.

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So first we make a list of car makers we we like called or favorite car makers called my favorite cars.

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Then we make a new list called Friends, Friends, Favorite Cars.

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And we make a copy of my favorite cars by asking for a slice of my favorite cars without specifying

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an indicator like this here.

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And assign the copy of my favorite cars to.

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Friend's favorite cars.

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So when and when we print each list, we see that they both contain the same cars.

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So to prove that we actually have two separate lists, we will add a new.

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Uh, we will add a new.

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Favor of a new car to each list and show that we that each list keeps track of the appropriate person's

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favorite car.

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So in order to do that, we will do after my favorite cars here we will do.

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My.

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My favorite cars that append here.

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Let's add new car maker name in this case, Toyota.

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Right.

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So Toyota.

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Of.

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Toyota here.

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And after that, we will also add friends favorite cars and we will append the.

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No, that's sad.

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Fiat, right?

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And here.

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We will not change this print functions and now we will run our code and see what will change here.

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And as you can see here, so we copy the original items in my favorite cars to the new list called Friends

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Favorite Cars, as we did in the previous example.

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And next we add a new favorite new car maker to each list and we add Toyota to my favorite cars and

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we add fiat to friends, favorite cars.

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And when and we then print the to list to see whether their whether each of these favorite cars in the

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is in the appropriate list.

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So here the output shows that our.

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Toyota is appears in our list of favorite cars.

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But Fiat here.

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Fiat does not.

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So we can see that Fiat now appears in our friends list.

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But Toyota doesn't write.

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If you had a simple set friend, favorite friends, favorite cars equal to my favorite cars, we will

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not produce two separate lists.

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For example, here's what happens when you try to copy a list without using a slice.

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Without using a slice.

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And as you can see here, we both have.

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So instead of assigning a copy of my foods to my my favorite cars, to my friend's favorite cars, we

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set a friend's favorite cars equal to my favorite cars.

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So this syntax actually tells Python to associate the new variable to my favorite cars with a list that

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is already associated with my favorite cars.

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So now my favorite cars.

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It will also appear in friends, favorite cars and so on.

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So likewise, the Toyota will appear in both lists, even though or Fiat will appear in both lists,

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even though it appears to be added only to my favorite cars.

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And as you can see here, Toyota and Fiat appears in the same list.

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So the output shows that both lists are the same now, which is not we wanted here and don't worry about

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the details in this example.

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For now, if you are trying to work with the with a copy of list and you see an expected behavior,

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make sure you are copying the list using a slice as we did in this in the first example here.