Let's cover the list data structure and why it's so wonderful.
In case you missed it, here are the previous parts of the series
0:00 Hey guys, what's up?
0:01 So in the last video I talked about string slicing.
0:06 In this video I'm gonna talk about lists, okay?
0:08 Lists of things and what the heck are lists.
0:11 Lists are awesome.
0:12 However, in the last video I left you guys with a question.
0:16 I said, take this,
0:20 right, and parse it.
0:21 And basically XBox 360, pull that out,
0:25 save it in a variable like product.
0:27 Pull this out, save it in a variable like price.
0:30 And save this in a variable like condition.
0:32 Right, so when you have your Excel sheet open,
0:35 it looks really nice, it'll look like this.
0:43 My solution, I'm gonna do it in a different way
0:47 because if you try to use it as index, this is the solution.
0:50 So you can pause the video, think about how it works.
0:53 That's how you'll pull the 150
0:55 and using the same logic, you'll pull the New.
0:57 However, index is a very ugly method to use
1:01 for getting, parsing the string.
1:04 What I want to show you guys is this method called find.
1:07 Okay, that's a very nice method.
1:09 Let's say we take the data, and I do data.find
1:14 and find, it shows you the bottom what it takes in
1:17 as the function, it takes in the substring
1:21 and then it takes in optional arguments, like start and n.
1:26 So I'm gonna say data.find
1:29 and I'll give it
1:30 substring pite.
1:33 What a substring means is that, that's something
1:37 that exists in the original string.
1:41 For example,
1:44 I have to give find,
1:45 the function find or the method find,
1:47 I have to give it something that exists within this.
1:50 If I gave it something that doesn't exist within it
1:52 like banana,
1:54 it would say negative one,
1:56 like I didn't find anything.
1:58 But if I gave it a pite, you can see that it finds a nine.
2:04 And another thing you can give it is how you solve...
2:09 Is you can give it where to start from, okay?
2:12 So I can say, for example,
2:15 start looking after ten
2:19 or look for pite,
2:21 but I want you to start at string nine,
2:25 Or I want you to start at string ten, alright?
2:29 And now it finds a pite at location 15.
2:32 So if I do data, and if you count it up,
2:35 you'll see that this is the pite
2:37 and it is at indeed at location 15.
2:39 If I do data(15), you'll see that
2:41 it gives you back that pite.
2:47 Okay, so by getting that second pite,
2:51 now you can get the value in between the first pite
2:54 and the second pite by saying something like,
2:59 start from finding the first pite
3:03 and then go up to
3:06 finding the second pite.
3:11 So I can say, finding,
3:14 or start from,
3:17 or look for pite.
3:19 And then start from ten, for example, right?
3:24 And this gives you this guy here.
3:26 And just to make sure we don't
3:27 include the pite in the first one
3:29 we can just start from plus one with that.
3:32 So that gives you in between the first and the second pite
3:34 you get probably like 150.
3:36 Okay, so,
3:38 the reason why I went even more in depth in strings
3:41 even when the video called lists
3:43 is because a lot of what you learn from strings
3:47 is applicable to lists, okay?
3:49 So, let's take a list and call it groceries.
3:54 And I will have apple, and I foreshadowed this
3:57 for you guys a little bit...
3:59 Banana--and you can also have integers.
4:01 Although usually you try to
4:02 put the same kind of thing in the list.
4:06 But sure, let's put five in there and six in there
4:09 and then oranges or something, okay?
4:13 Now, if I wanna
4:15 take this list
4:17 and I wanna get the first element and the second element,
4:19 if it was just a string,
4:22 Like the reason why lists are useful is 'cause
4:24 you can use it to store multiple variables.
4:29 Like for example, if you wanted to use variables
4:31 to store this, aww shh--
4:34 It would be a little...
4:38 It would be weird.
4:39 'Cause you will say groceries, zero is equal to apple.
4:43 You would say...
4:51 Groceries of one are banana.
4:53 And so then when you do groceries of zero,
4:55 you get back apple.
4:57 And when you do groceries of one,
5:00 you get back banana.
5:02 But lists make it, make that thing,
5:05 for you in a really easy way, okay?
5:09 So now, if I do groceries and if I do groceries of zero,
5:14 I get back apple, okay?
5:16 And if I do groceries of one, I get back banana.
5:19 Because apple is in the zero position.
5:22 Banana is in the first position.
5:25 This is in the second, third, fourth position, okay?
5:30 So lists make it really nice for you.
5:33 Imagine if you were trying to store data for a race.
5:36 So like, four of your friends ran really fast
5:40 and you wanted to record who came first, who came second.
5:43 So you can save
5:46 race is equal to
5:49 like John came first, and then Bob came second,
5:53 and then, you know, whatever, like Timothy came in third,
5:59 uh, Timothy is pretty slow. (laughs)
6:03 So we can say like, okay, who came in first?
6:07 We can ask that question.
6:08 We get back John.
6:09 We can say, who came in second?
6:11 We get back Bob.
6:12 And I can say, who came in third?
6:14 Or I can say who came in last?
6:17 That negative one gets you the last element.
6:19 And this answers all my questions.
6:22 So just like how were able to slice strings,
6:26 we're able to slice
6:28 lists, okay?
6:30 But notice, lists is nicer for elements.
6:33 So for example,
6:35 XBox 360 and all this stuff,
6:38 I'll show you guys a really cool trick you can do with lists
6:41 to break that up into pieces.
6:43 So like for example,
6:46 if I gave you a string like this, right,
6:48 what is going on?
6:50 Notice that there are a lot of spaces in between, right?
6:52 Let's just replace those spaces,
6:54 just so it's more visual,
6:56 let's replace those space with that,
6:59 and let's say we want to get the what part separately,
7:02 is part separately, going part separately,
7:04 and on part separately,
7:07 without having any of the dashes in the middle.
7:10 There's a method we can use called .split, okay?
7:14 And we can pass to .split what we want to split by.
7:19 So I can say something like this,
7:21 I want to split by the dashes, okay?
7:23 So check it out, now I got what is going on, right?
7:27 This is a list
7:30 of strings.
7:31 Now the data complexity is getting a little bit higher,
7:34 it's a list containing strings inside of it.
7:39 Okay, so, I can call this like,
7:43 you know,
7:46 greeting or something, it doesn't matter,
7:48 and if I do greeting, I can say
7:50 What's the first word of greeting?
7:53 What's the second word?
8:02 Greeting, right, what's the second word?
8:05 And for example, I can say what's the last word?
8:09 And it'll give me what is going on,
8:11 on being the last word, right?
8:13 Now, I can also do string slicing just like
8:17 how I can do in strings.
8:19 So I have start, I have stop,
8:22 and I have step.
8:24 So if I take the race one again,
8:27 I can say go from zero all the way to the end.
8:31 I can say the same way, like this,
8:35 this is like optional, right?
8:38 It starts with zero and it ends at zero,
8:40 or ends at the last one by default.
8:43 If I wanna get from John to Bob,
8:46 I can say like give me the
8:47 first two...
8:50 first two contestants of the race.
8:53 And it will give me John and Bob.
8:55 Or I'll say give me everybody but the last guy
8:58 so I can ask that question to my list, just like that.
9:04 Okay, now to answer your guys' question
9:06 of how to reverse the string,
9:08 it's the same you can reverse the list as well.
9:12 So, lemme show you guys.
9:14 There are a couple of different ways,
9:15 but I'm gonna show you guys the nicest, the fanciest way.
9:20 So let's take this list
9:23 and I wanna step by...
9:26 Sorry, I wanna start at the default, which is zero.
9:29 I don't have to write zero,
9:30 but I'll just write it for you guys.
9:32 I want to go all the way to the end
9:34 and I don't have to write this, okay?
9:36 So I'll just leave it blank here.
9:39 And for the last part, for step,
9:42 instead of saying step by one,
9:44 which will just give me the whole thing.
9:47 Instead of saying give me every other element,
9:49 so like give me John and then Timothy
9:52 I will say
9:55 step by negative one.
9:57 So check this out,
10:00 let's remove
10:06 And let's remove that guy, and let's do that,
10:09 and you will see how it steps.
10:14 It just reversed the list.
10:17 If we have
10:18 the same string, like
10:20 let's say we have data I can do the same way and
10:25 reverse everything in data.
10:28 So you can see XBox 360 and New and 150
10:31 are all written backwards, okay?
10:35 So that's how you would like reverse something.
10:38 Now I want to talk about
10:43 split again,
10:44 and I want to talk about one very important method
10:48 called a pen for a list.
10:50 One of the most commonly used things
10:53 that any programmer does in any language, okay?
10:57 So split is like Java, Cs, everybody uses that.
11:01 It just might not be called split.
11:02 And the same thing in Python, everybody uses split
11:05 and the next method I'm about to show you, pen.
11:07 Very common for all the games you make,
11:10 for everything that you do, it's going to be like
11:11 one of the most common thing you use,
11:13 especially a pen, so pay attention.
11:15 So I'm gonna show you
11:18 the method called
11:20 the split, okay?
11:22 So I've shown you a little bit of that already.
11:23 So let's say I take data and I wanna break it up,
11:27 right, product, price, condition.
11:31 Very easy way to do it, very easy way to do it split.
11:33 So let's use data.split,
11:36 and I wanna say split by
11:41 Boom, look at that.
11:42 How nice is that, right?
11:44 It automatically just split it by that
11:46 and you can store that in
11:50 details or something.
11:52 And now if I do details of zero,
11:57 and I can set that equal to product.
12:00 So now if I do product, I get that.
12:03 I can say
12:05 price is equal to
12:09 of one
12:10 and I can say condition
12:13 is equal to details
12:14 of two.
12:16 Okay, price, condition,
12:21 So that was like some really nice ways to get this done.
12:24 In the next video I will talk about a pen.
12:27 So stay tuned.