Lists |Section 1| Celestial Warrior

1

Show more

00:00:01,550 --> 00:00:08,189

Great, now let's look at lists, so in the

previous lecture we were looking at

3

00:00:08,189 --> 00:00:14,250

strings and indexing and splitting

strings and I will be working with lists

5

00:00:14,250 --> 00:00:20,210

which are very similar to strings. They

are similar because they are both

7

00:00:20,210 --> 00:00:25,949

referred to as sequences, so there are

sequences of items. The difference is

9

00:00:25,949 --> 00:00:35,910

that, let me open Python, and so the

difference is that the string is made of

11

00:00:35,910 --> 00:00:41,730

other strings so it can contain only

strings of characters or strings.

13

00:00:41,730 --> 00:00:49,079

whatever you like to call it, however

lists can contain various other data

15

00:00:49,079 --> 00:01:00,809

types, let's say H a letter, a number, and

also a string. So this is a string the

17

00:01:00,809 --> 00:01:05,970

first one, this is a number, an integer.

This is also string with multiple

19

00:01:05,970 --> 00:01:14,460

characters and that is a list, so for

this you want to use square brackets to

21

00:01:14,460 --> 00:01:21,450

create a list. Execute and yeah you can

call it and so this is a list of three

23

00:01:21,450 --> 00:01:26,460

items and you can also store other

objects in a list but we'll cover other

25

00:01:26,460 --> 00:01:33,320

objects in later sections, you know we

have table of objects with lots of data.

27

00:01:33,320 --> 00:01:39,180

You may store files in a list you may

store widgets of a graphical user

29

00:01:39,180 --> 00:01:45,570

interface that you are building and so

on, so these are very useful and lists also

31

00:01:45,570 --> 00:01:51,180

have indexing and you can split lists,

you can extract items and so on. So the

33

00:01:51,180 --> 00:01:56,790

good news is that lists have the

same indexing system as strings and so

35

00:01:56,790 --> 00:01:59,790

you've learned that in the previous

lecture and you can go ahead and apply

37

00:01:59,790 --> 00:02:06,979

that system not, so let's extract number 2.

That would have an index of one.

39

00:02:06,979 --> 00:02:14,720

Execute that and yeah you get 2 there. If you

check the type you'll see that's an integer.

41

00:02:14,720 --> 00:02:20,760

So every item of a list has its own

data type, even also access more than

43

00:02:20,760 --> 00:02:28,970

white one item of a list. Let's say

you want the first two items. You do 0 1 2, so

45

00:02:28,970 --> 00:02:38,010

like that or 0 to 2 whatever you like.

That will produce another list so the

47

00:02:38,010 --> 00:02:49,459

type of this split is a list. The type of

the split of a string is a string, so S

49

00:02:49,459 --> 00:02:57,390

for the string here, C for the list.

Lists now have methods associated with

51

00:02:57,390 --> 00:03:02,130

them just like strings do and so you can

check what methods you have available

53

00:03:02,130 --> 00:03:08,220

there by just doing a dir list.

So this a the blueprint you can use

55

00:03:08,220 --> 00:03:13,200

lists, you can pass empty square brackets

in there, it's the same thing and then

57

00:03:13,200 --> 00:03:20,510

you can use help to look at each of

these methods, so these are the methods.

59

00:03:20,510 --> 00:03:31,260

Without the underscore and let's look at

the append method, so to apply methode

61

00:03:31,260 --> 00:03:39,690

you do c the dot notation append and here

on that 3. What that does, it adds

63

00:03:39,690 --> 00:03:44,549

another item to the end of the list,

So it appends an item to the

65

00:03:44,549 --> 00:03:49,850

list and you can explore the other

methods if you like so let's say help.

67

00:03:49,850 --> 00:03:59,160

Remove like that and you'll see how to

use that remove method, so you do

69

00:03:59,160 --> 00:04:03,750

c.remove and then you pass the value of

the item that you want to remove, so

71

00:04:03,750 --> 00:04:10,440

not the index but the value. Let's say we

want to remove 2 and you see that 2

73

00:04:10,440 --> 00:04:16,979

is now gone from the list so look

at the other methods of the list and try

75

00:04:16,979 --> 00:04:21,720

to experiment with this and play around

with them access items and split them

77

00:04:21,720 --> 00:04:27,470

and you'll be good to go then.

Thanks, I'll talk to you later.

Show less