1 00:00:00,140 --> 00:00:00,470 OK. 2 00:00:00,480 --> 00:00:02,540 Now let's talk about lists. 3 00:00:02,670 --> 00:00:05,250 So lists are data structures. 4 00:00:05,250 --> 00:00:09,720 Now these data structures are changeable that we can re order them. 5 00:00:09,720 --> 00:00:11,970 Put them in a list. 6 00:00:11,970 --> 00:00:12,270 Right. 7 00:00:12,270 --> 00:00:14,180 So they're just a group of elements. 8 00:00:14,220 --> 00:00:19,830 And when you when you have this list everything inside that list is called an item. 9 00:00:19,830 --> 00:00:24,330 And the best way to think of a list is to think that it lives in between brackets. 10 00:00:24,330 --> 00:00:30,510 You're going to see other things later on that look like a list but it's not really a list because of 11 00:00:30,810 --> 00:00:36,900 how it's defined and how we're going to define lists is because they live in brackets just like a string 12 00:00:36,900 --> 00:00:38,430 might have quotes around it. 13 00:00:38,430 --> 00:00:40,430 A list is going to have these brackets around it. 14 00:00:40,500 --> 00:00:48,390 So let's make a new line and let's go ahead and just do something along the lines of lists and we could 15 00:00:48,430 --> 00:00:53,490 say something like have the brackets like this. 16 00:00:54,630 --> 00:00:55,410 OK. 17 00:00:55,650 --> 00:00:59,680 So let's go ahead and make a list and then we can kind of go from there. 18 00:00:59,700 --> 00:01:03,090 So let's define a list of your favorite movies. 19 00:01:03,090 --> 00:01:08,820 Now you can put in whatever favorite movies you like in here and I'm going to put in something like 20 00:01:10,200 --> 00:01:11,550 When Harry Met Sally 21 00:01:15,470 --> 00:01:16,580 the hangover 22 00:01:19,850 --> 00:01:28,100 The Perks of Being A Wallflower and this is getting kind of long so I'm actually going to move this 23 00:01:28,100 --> 00:01:33,490 over a little bit for us and we'll say one more let's pick for movies. 24 00:01:33,500 --> 00:01:35,080 We'll do the exorcist. 25 00:01:35,740 --> 00:01:36,160 OK. 26 00:01:37,040 --> 00:01:40,660 And now we have this this list again list. 27 00:01:40,670 --> 00:01:41,930 Just live in brackets. 28 00:01:41,940 --> 00:01:48,340 So we've got list item one item two item three and item for OK. 29 00:01:48,390 --> 00:01:50,580 So let's go ahead and print these. 30 00:01:50,580 --> 00:01:59,070 So if we were to print out something like movies and we said we wanted to print the first item out of 31 00:01:59,070 --> 00:02:01,560 movies let's go ahead and try to print When Harry Met Sally. 32 00:02:01,590 --> 00:02:07,560 So print the first item so put a bracket around it just like this or print it out and we'll see what 33 00:02:07,560 --> 00:02:08,610 happens. 34 00:02:08,640 --> 00:02:09,520 So let's say that. 35 00:02:09,870 --> 00:02:15,780 And what's it going to return for us it's returning the hangover. 36 00:02:15,780 --> 00:02:20,190 So item one is not item one as you see it. 37 00:02:20,580 --> 00:02:28,660 So when we talk about items and we talk about numerical order here in Python item one is actually going 38 00:02:28,660 --> 00:02:31,050 to be referred to as zero. 39 00:02:31,060 --> 00:02:35,540 So make a note here for yourself that this will return. 40 00:02:35,590 --> 00:02:37,890 The second item. 41 00:02:38,290 --> 00:02:45,820 So if we wanted to return just When Harry Met Sally we would actually put in movies Zero like this and 42 00:02:45,820 --> 00:02:51,340 we could say returns the first item in the list. 43 00:02:51,950 --> 00:02:52,500 OK. 44 00:02:52,570 --> 00:02:57,000 And we can say that and let's go ahead and give it a go. 45 00:02:57,000 --> 00:02:58,500 Just to do proof of concept. 46 00:02:58,500 --> 00:02:59,670 And there you go. 47 00:02:59,670 --> 00:03:03,330 Remember that everything starts with zero and not one. 48 00:03:03,330 --> 00:03:07,820 So when you're thinking about things let's think about them with zero as the beginning. 49 00:03:07,830 --> 00:03:09,550 No. 50 00:03:09,720 --> 00:03:13,020 So let's go ahead and do a few more different prints. 51 00:03:13,020 --> 00:03:15,840 What's gonna happen when we print out something like this. 52 00:03:15,840 --> 00:03:21,270 We'll say movies and we'll do one through three. 53 00:03:21,450 --> 00:03:22,450 You have a hunch. 54 00:03:22,500 --> 00:03:24,090 Let's go ahead and save it. 55 00:03:25,670 --> 00:03:35,730 Print it out here and it will take the list here of starting at 1 and it'll end before 3. 56 00:03:35,770 --> 00:03:40,090 So let's say we want to pull a couple of items out the first number that we're going to pull out is 57 00:03:40,090 --> 00:03:42,430 going to be the one that we want to start with. 58 00:03:42,490 --> 00:03:47,620 And the last number that we're going to pull out is going to be the number where we're going to stop. 59 00:03:47,650 --> 00:03:49,770 So the X axis is three. 60 00:03:49,800 --> 00:03:55,330 But if we wanted to actually pull down the axis we would have to pull down four here. 61 00:03:55,330 --> 00:03:59,260 So if we want to try to grab more than one thing on the list we can absolutely do that. 62 00:03:59,380 --> 00:04:01,030 But we have to know where to stop. 63 00:04:01,030 --> 00:04:04,150 So now we incorporate the exorcist here. 64 00:04:04,210 --> 00:04:10,420 Let's say we want to grab everything in a list and we wanted to grab everything after a certain point. 65 00:04:10,420 --> 00:04:10,720 Right. 66 00:04:10,720 --> 00:04:18,760 We could say something like movies one like this and then we should be able to grab every single thing 67 00:04:20,710 --> 00:04:23,610 and that does pretty much the same thing here. 68 00:04:23,610 --> 00:04:30,630 So if we had 30 items here it would grab all 30 items in this list if we wanted to grab three items 69 00:04:30,690 --> 00:04:32,970 as we did before we would do one. 70 00:04:33,180 --> 00:04:35,720 And then you just add three to that to four. 71 00:04:35,730 --> 00:04:37,050 And it would stop. 72 00:04:37,050 --> 00:04:38,460 So a little bit confusing. 73 00:04:38,490 --> 00:04:40,800 This takes a little bit to wrap your mind around. 74 00:04:41,340 --> 00:04:47,010 But the good thing here is that you take notes you can make notes however you feel comfortable with. 75 00:04:47,400 --> 00:04:50,200 And these tricks should be useful for you. 76 00:04:50,220 --> 00:04:52,530 So let's try another thing. 77 00:04:52,530 --> 00:04:57,060 What if we said something like movies and we did this one in reverse. 78 00:04:57,090 --> 00:05:02,390 We just did something like this when we did save Let's print it out. 79 00:05:02,400 --> 00:05:08,050 What do you think's going to have an it's going to print When Harry Met Sally because it's going to 80 00:05:08,050 --> 00:05:14,950 stop at the one we never get to one here again similar situation when we had this set of three we never 81 00:05:14,950 --> 00:05:16,500 get to one we stop at one. 82 00:05:16,540 --> 00:05:22,210 So we're gonna grab everything before one which is going to be just be When Harry Met Sally we could 83 00:05:22,210 --> 00:05:25,430 set this to two and we would grab the hangover in this as well. 84 00:05:25,600 --> 00:05:27,180 And just to prove concept here. 85 00:05:27,600 --> 00:05:29,470 So that I'm not crazy. 86 00:05:29,470 --> 00:05:34,120 You can see here the hangover gets added in because we get zero and we grab one. 87 00:05:34,180 --> 00:05:41,590 You could also think of this if you don't confuse herself as grabbing two items out of the list but 88 00:05:41,590 --> 00:05:46,600 make sure you don't confuse yourself because if this number were to be like two through four then it 89 00:05:46,600 --> 00:05:48,190 would be something completely different. 90 00:05:48,190 --> 00:05:48,920 Right. 91 00:05:48,970 --> 00:05:53,120 So you need to make sure that you understand where from the list that you're actually grabbing where 92 00:05:53,210 --> 00:05:55,290 Senate controls ease back. 93 00:05:56,190 --> 00:06:02,590 So from here let's do two more tricks. 94 00:06:02,590 --> 00:06:06,780 Actually we'll do one more trick and they'll move into some other items related to lists. 95 00:06:06,790 --> 00:06:15,460 So if we say movies like this and we want to grab the very last item we can just put in a negative one 96 00:06:16,300 --> 00:06:19,320 and so grab the absolute last item off the list. 97 00:06:19,450 --> 00:06:20,030 That way. 98 00:06:20,140 --> 00:06:24,480 If you have a list that's two thousand items long and you don't know where it ends. 99 00:06:24,490 --> 00:06:25,630 You could just do negative one. 100 00:06:25,630 --> 00:06:31,180 It's going to grab the last item for you and then you can see there it grab down the exorcist. 101 00:06:31,360 --> 00:06:37,870 So cool little tricks you might not use these for a while and you probably won't see these come through 102 00:06:37,870 --> 00:06:41,950 at least in anything we're going to really do in the course but they're still incredibly useful to know 103 00:06:41,950 --> 00:06:45,540 about because they're they are included in the basics of Python. 104 00:06:45,550 --> 00:06:52,060 So you're going to know the basics of Python and you will use these sometime in your lifetime. 105 00:06:52,060 --> 00:06:57,670 It's useful to know this kind of stuff so we can also do some things with list as well. 106 00:06:58,060 --> 00:07:06,850 We can print out the length of our lists so we can say length of movies something like this and get 107 00:07:06,850 --> 00:07:10,300 that ago and you can see that there's four items in that list. 108 00:07:10,990 --> 00:07:16,010 So we've seen length before with strings and it took every single character inside that string. 109 00:07:16,060 --> 00:07:21,180 Here it's taking every single amount of item inside a list and pointing that out. 110 00:07:21,250 --> 00:07:27,300 We can also append items to the list so we can say something like movies dot a pen. 111 00:07:27,310 --> 00:07:31,320 And what if we really like Jaws and we add that into our favorite movies. 112 00:07:31,450 --> 00:07:33,220 You can have too many favorite movies come on. 113 00:07:33,280 --> 00:07:40,630 So let's go ahead and try printing that out and while we have to actually print it sorry movies out 114 00:07:40,630 --> 00:07:47,860 of hand and then we say print movies now and it should print out with jobs added in. 115 00:07:47,860 --> 00:07:53,370 Where do we think jobs is going to actually add itself into well if you said the end of the list you 116 00:07:53,370 --> 00:07:54,790 are correct. 117 00:07:54,790 --> 00:08:00,600 So when we append something we append it to the very end of the list. 118 00:08:00,730 --> 00:08:06,880 What if we wanted to delete something from the list we could say something like this movie stop pop 119 00:08:08,440 --> 00:08:11,110 and print movies. 120 00:08:11,200 --> 00:08:12,360 Let's see what happens here 121 00:08:18,390 --> 00:08:20,110 and now we got rid of Jaws. 122 00:08:20,130 --> 00:08:25,470 So when we append We append to the end of the list if we want to delete the very last item in the list 123 00:08:25,860 --> 00:08:27,630 we just use pop. 124 00:08:27,690 --> 00:08:35,280 Now if we wanted to delete something like the first item or the second item we could do movies that 125 00:08:35,280 --> 00:08:40,010 top and let's say 0 print movies. 126 00:08:40,840 --> 00:08:46,010 So remove the very very first item in the list we should see you inherently disappear. 127 00:08:46,380 --> 00:08:47,100 And there you go. 128 00:08:47,100 --> 00:08:50,500 No longer is When Harry Met Sally and our list. 129 00:08:50,520 --> 00:08:53,810 So this is a quick way that we can remove these items. 130 00:08:54,060 --> 00:08:58,340 And on the fly if we need to to get rid of this. 131 00:08:58,440 --> 00:09:04,830 So the high level overview here and the thing that you really need to take away is that list have brackets. 132 00:09:04,830 --> 00:09:07,220 We're going to see something called dictionaries later. 133 00:09:07,230 --> 00:09:14,250 We might see something called tuples later and they all look very very similar but here lists have brackets 134 00:09:14,580 --> 00:09:19,170 inside those brackets are what we have that are called items. 135 00:09:19,270 --> 00:09:19,650 OK. 136 00:09:19,650 --> 00:09:22,590 And there are many different ways to return items. 137 00:09:22,650 --> 00:09:27,900 The reason that I'm showing you these different ways is so that you can get familiar with the syntax 138 00:09:28,350 --> 00:09:36,690 that we start our list or our items with zero and not one and that we can grab from these lists in different 139 00:09:36,690 --> 00:09:37,840 ways. 140 00:09:37,860 --> 00:09:38,310 OK. 141 00:09:38,310 --> 00:09:43,890 And this will come back into play later with how we can utilize this same kind of syntax with other 142 00:09:43,890 --> 00:09:50,730 items as well or other things in Python so we can also utilize you know printing out length or we can 143 00:09:50,730 --> 00:09:57,810 do a append and add to the list or dot pop and there's a lot of different things that we can do here 144 00:09:58,260 --> 00:10:02,280 to you know to append to these lists or remove from these lists et cetera. 145 00:10:02,310 --> 00:10:08,250 So this is just the basics but hopefully what you take away from this is that lists have brackets and 146 00:10:08,600 --> 00:10:13,300 you know the items there are items in the list and they start with zero. 147 00:10:13,320 --> 00:10:14,760 Those are the key takeaways. 148 00:10:14,760 --> 00:10:21,300 So in the next video we're going to briefly talk about tuples and then we're gonna move on into looping. 149 00:10:21,300 --> 00:10:22,620 So let's go ahead and do that.