Lecture 3.2 - List Methods

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Del curso dictado por University of California, Irvine

The Raspberry Pi Platform and Python Programming for the Raspberry Pi

1295 calificaciones

University of California, Irvine

The Raspberry Pi Platform and Python Programming for the Raspberry Pi

1295 calificaciones

Curso 4 de 6 en SpecializationAn Introduction to Programming the Internet of Things (IOT)

The Raspberry Pi is a small, affordable single-board computer that you will use to design and develop fun and practical IoT devices while learning programming and computer hardware. In addition, you will learn how to set up up the Raspberry Pi environment, get a Linux operating system running, and write and execute some basic Python code on the Raspberry Pi. You will also learn how to use Python-based IDE (integrated development environments) for the Raspberry Pi and how to trace and debug Python code on the device. Please note that this course does not include discussion forums.

De la lección

Module 3

We present the basics of the Python programming language to prepare you for programming on the Raspberry Pi. Many languages can be used but Python is the most convenient for the Raspberry Pi because convenient APIs are provided for basic operations such as controlling the pins. Python is a powerful language with useful features that we will present so that you can use these features to control the Raspberry Pi.

Lecture 3.1 - Lists3:37

Lecture 3.2 - List Methods3:21

Lecture 3.3 - Control Flow5:38

Conoce a los instructores

Ian Harris
Professor
Department of Computer Science

[MUSIC]

List methods are very similar to list operators.

The main difference is that list methods are invoked in a different way.

They're invoked on a list, so

you have to use the name of the list that you're invoking the operation on.

You use that name in the invocation, you prefix it actually.

So let's just take a look.

So you've got a list, [1, 2, 3], and you want to append something to the list,

meaning add a number 8 onto the end of the list.

So there's a list method called append.

And the way you invoke is you say, list.append, and

in parentheses you pass 8.

So what that will do is it'll take this list, lst, which we just defined, and

it will append 8 onto that list.

Notice that one of the arguments is append,

this append operator is working on list.

But list is not an explicit argument to the append function, right?

You prefix the whole invocation with the list, lst., right?

So what happens underneath the hood is it basically takes that list and

passes it to the append function.

But it's just a different way of doing the same thing, for

all appearances sake it looks different, but it does the same thing, okay.

So there are several methods like this where you invoke them by starting off

by prefixing the invocation with the name of the list that you wanna operate on.

And then a dot and then you give the name of the function or the method.

So now if you print that list after doing this append, it's [1, 2, 3, 8], so

it did its job.

So there's a set of list methods, here's some list methods.

The most common ones anyway.

lst.append, it does just what we saw, it appends an item onto a list.

lst.count, it returns the number of times a particular item appears in a list.

lst.index for

a particular item, it returns the index of the first occurrence of the item.

So if you have that list that we just saw, [1, 2, 3, 8], and

I said lst.item for 8, it would return 3, right?

Because that's the third element starting at 0, 0, 1, 2, 3, it's the third element.

Pop.

Pop removes the last item out of a list, and it returns the item, okay?

So pop, and that's different than lst.remove, if you look at

lst.remove which is the next one, it just removes the item from the list.

It will remove an arbitrary item from the list.

but pop removes the first item, but it also returns,

oh, excuse me, pop removes the last item, and it returns the last item,

where lst.remove doesn't return anything, so there's a difference there.

lst.reverse, it doesn't return anything, it reverses the order of the list,

reverses the order of the elements in the list.

And lst.sort, it doesn't return anything, it just sorts the element of the list in

increasing order for whatever the elements are.

So if it's alphabetical or alphanumeric, it just sorts them in alphanumeric order.

Yeah and append, remove, reverse and sort don't actually return any values,

they just modify the list, they don't return anything.

Thank you.

[MUSIC]

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