1 00:00:00,940 --> 00:00:01,930 Hey, welcome back. 2 00:00:01,960 --> 00:00:07,260 In this video, you learn about the difference between an instance method and a class methods. 3 00:00:07,270 --> 00:00:10,120 We did cover instance methods so far. 4 00:00:10,150 --> 00:00:13,730 So all these here are instance methods. 5 00:00:13,750 --> 00:00:17,590 Syntactically, you can tell that something is an instance method. 6 00:00:17,590 --> 00:00:22,200 When you see that self is the first parameter. 7 00:00:22,210 --> 00:00:30,610 All of that methods logically what makes an instance method and instance method is that the method? 8 00:00:31,450 --> 00:00:35,560 Can be applied to an instance, Right. 9 00:00:35,560 --> 00:00:44,350 So we can check here, for example, hotel one that available. 10 00:00:44,800 --> 00:00:47,860 So perhaps print out its output. 11 00:00:50,290 --> 00:00:55,330 Let me remove this last line, because as you saw in the previous video, that was to show you that 12 00:00:55,480 --> 00:00:57,850 that line produced an error. 13 00:00:58,240 --> 00:01:04,450 So now we should see true print it out out of available. 14 00:01:04,780 --> 00:01:10,390 So the method is an instance method because it can be applied to hotel one and it can also be applied 15 00:01:10,390 --> 00:01:11,410 to Hotel two. 16 00:01:11,440 --> 00:01:17,350 So an instance method is very tightly associated with its instance. 17 00:01:17,560 --> 00:01:23,050 So you are checking if this particular instance, this particular hotel. 18 00:01:24,200 --> 00:01:25,910 Whose name is. 19 00:01:27,140 --> 00:01:28,760 Snow palace. 20 00:01:29,780 --> 00:01:32,570 If this particular hotel is. 21 00:01:34,040 --> 00:01:36,170 Available or not. 22 00:01:36,950 --> 00:01:40,050 The same goes with other methods such as book. 23 00:01:40,070 --> 00:01:42,770 You are booking that particular hotel. 24 00:01:43,550 --> 00:01:46,310 Same goes with reservation tickets. 25 00:01:46,550 --> 00:01:52,010 You are generating a particular instance of the reservation tickets. 26 00:01:52,010 --> 00:01:53,450 You are printing that out. 27 00:01:54,470 --> 00:01:57,200 But what is a class method then? 28 00:01:59,270 --> 00:02:01,840 And when would you need a class method? 29 00:02:01,850 --> 00:02:04,790 So let's create a class methods here. 30 00:02:05,840 --> 00:02:09,800 To create a class method, you use the diff keyword. 31 00:02:09,800 --> 00:02:15,860 Again, pick a name for the class methods such as hotel count. 32 00:02:16,190 --> 00:02:17,630 Get hotel count. 33 00:02:18,630 --> 00:02:24,700 Now instead of self with class methods, you write something like C. 34 00:02:24,720 --> 00:02:29,220 Else I'll cover in just a bit what classes. 35 00:02:29,640 --> 00:02:35,130 And then perhaps other arguments such as DF or data. 36 00:02:38,140 --> 00:02:39,940 And then hear Return. 37 00:02:40,240 --> 00:02:40,860 Len. 38 00:02:41,590 --> 00:02:42,310 So. 39 00:02:43,630 --> 00:02:54,400 I just created a class method which will return the length of the data frame, which means that, for 40 00:02:54,400 --> 00:02:57,720 example, for this particular data frame we will get three. 41 00:02:57,730 --> 00:03:00,040 This will return three, right? 42 00:03:00,040 --> 00:03:03,370 Because this does a frame has three rows. 43 00:03:03,580 --> 00:03:15,340 And lastly, to finalize this method, you should add the class method decorator just above the function. 44 00:03:15,340 --> 00:03:17,650 So don't leave any brake lines here. 45 00:03:17,680 --> 00:03:28,090 This is a recommended style, so that decorator will basically change this method to a class method. 46 00:03:28,120 --> 00:03:33,220 Now class, this can also be self write because it's just a variable. 47 00:03:33,640 --> 00:03:43,720 But to be in line with best practices, you should use seals here because this actually will be a variable 48 00:03:43,720 --> 00:03:48,400 which will hold the class object, not the instance object. 49 00:03:48,400 --> 00:03:51,290 So everything in Python is an object, right? 50 00:03:51,310 --> 00:03:57,550 So when you go to a Python console, for example, and you do class A. 51 00:03:59,100 --> 00:04:01,230 Let me pass just a simple class. 52 00:04:01,650 --> 00:04:05,940 A is an object, but a. 53 00:04:07,270 --> 00:04:09,790 The instance of A is also an object. 54 00:04:10,700 --> 00:04:11,900 So that means. 55 00:04:13,410 --> 00:04:14,640 In class. 56 00:04:15,460 --> 00:04:18,010 This variable will hold the class. 57 00:04:18,040 --> 00:04:20,649 Now, why did I add this method to you? 58 00:04:20,680 --> 00:04:23,210 Well, this method, as you'll see. 59 00:04:23,230 --> 00:04:25,000 So let me call it here. 60 00:04:25,000 --> 00:04:27,490 Print Hotmail dot. 61 00:04:28,240 --> 00:04:29,080 Get. 62 00:04:31,920 --> 00:04:33,120 Hotel count. 63 00:04:33,150 --> 00:04:38,580 Underscore hotel count with parentheses. 64 00:04:39,240 --> 00:04:41,010 And it needs a. 65 00:04:41,610 --> 00:04:42,600 An argument. 66 00:04:42,600 --> 00:04:49,710 The data argument will be equal to d f our data frame which is assigned here as a global variable and 67 00:04:49,710 --> 00:04:50,310 run. 68 00:04:52,150 --> 00:04:54,100 And we get three printed out. 69 00:04:54,550 --> 00:04:58,270 So notice that I used hotel the class. 70 00:04:59,230 --> 00:05:00,460 Here boats. 71 00:05:00,460 --> 00:05:06,730 You can also access a class variable using an instance. 72 00:05:06,730 --> 00:05:15,190 So Hotel one is an instance I've created up here, and if I run this, we'll get to threes printed out. 73 00:05:16,450 --> 00:05:19,030 One for that and one for that. 74 00:05:19,060 --> 00:05:23,980 Now, you might ask, well, shouldn't this method also be an instance method? 75 00:05:24,490 --> 00:05:29,140 Well, not because it's this is not related to a particular instance. 76 00:05:29,830 --> 00:05:30,340 Right. 77 00:05:30,340 --> 00:05:33,420 This is related to the class somehow. 78 00:05:33,430 --> 00:05:38,920 So it's about hotels, but it's not related to a particular hotel. 79 00:05:39,190 --> 00:05:45,670 It's not related either to tourist sunny apartment nor to snow palace or city break in. 80 00:05:46,740 --> 00:05:54,450 So whenever you need a method which is somehow related to the class but not related to an instance, 81 00:05:54,450 --> 00:06:04,800 then you want to create a class methods and you use that class method decorator and that seals parameter. 82 00:06:05,010 --> 00:06:06,740 And that's about class methods. 83 00:06:06,750 --> 00:06:09,750 I hope that makes sense and I'll talk to you in the next video. 84 00:06:09,750 --> 00:06:10,170 Thanks.