WEBVTT 00:00.290 --> 00:00.830 Hi everyone. 00:00.830 --> 00:02.180 Welcome back to this tutorial. 00:02.180 --> 00:10.100 In this tutorial we will code and explore the max by with grouping by and min by with grouping by. 00:10.130 --> 00:17.870 And the use case that we are going to create is that we are going to calculate the top student in each 00:17.870 --> 00:21.350 grade and the least student in each grade. 00:22.030 --> 00:22.590 Let's cut. 00:22.600 --> 00:30.550 Let's cut the top student first, and then we'll cut the least student public required. 00:30.910 --> 00:33.520 And then it is going to be calculate. 00:34.580 --> 00:34.990 Top. 00:36.120 --> 00:36.500 EP. 00:38.680 --> 00:38.980 Okay. 00:38.980 --> 00:45.760 And then we're going to do student database dot, get all students and then call the string method. 00:45.790 --> 00:46.810 We're going to do that. 00:46.810 --> 00:52.150 And followed by that, what we are going to do, we are going to do the collect operation. 00:52.180 --> 00:58.420 The collect operation is going to take group by and then we are going to pass a key because we want 00:58.420 --> 01:02.380 to know the top student in each grade, right? 01:02.380 --> 01:06.910 So the key is going to be student colon, colon grade level. 01:06.970 --> 01:10.990 And then followed by that, we are going to do a max by. 01:12.300 --> 01:12.690 Right. 01:12.690 --> 01:14.250 So this is again a collector. 01:14.250 --> 01:22.110 And then we are going to give comparator dot comparing and we are going to pass the student colon. 01:22.110 --> 01:22.770 Colon. 01:23.740 --> 01:26.140 Let me put this down here so that it will be clear. 01:26.170 --> 01:26.890 Student Colon. 01:26.890 --> 01:27.370 Colon. 01:27.370 --> 01:28.480 Get GPA. 01:29.970 --> 01:31.550 So this is what we are going to do. 01:31.600 --> 01:33.190 Let's review this code again. 01:33.210 --> 01:38.520 Here we are performing grouping by along with Max, by if we take a look at it. 01:38.520 --> 01:41.400 This is the two argument version of grouping by. 01:41.430 --> 01:46.950 So we are passing the grade level and then in the comparing we are passing the GPA. 01:46.950 --> 01:50.520 So this is going to give you a map. 01:52.390 --> 01:56.200 Map of integer, which is a grid. 01:56.200 --> 02:00.760 And then if you take a look at the max by max by will always return optional. 02:00.790 --> 02:03.640 That's going to be optional. 02:06.440 --> 02:06.800 Didn't. 02:08.590 --> 02:14.530 And then we are going to give the name as turn map optional. 02:15.190 --> 02:15.880 There you go. 02:16.000 --> 02:17.350 Let's print this one. 02:23.150 --> 02:24.260 And print this. 02:25.490 --> 02:29.000 Let's execute this and then check the result. 02:29.030 --> 02:29.630 What is that? 02:29.630 --> 02:30.680 It is going to have. 02:34.080 --> 02:34.650 This. 02:35.570 --> 02:38.560 The sprinting for the second grade. 02:38.570 --> 02:43.550 Jenny is the student who is having the top grade, which is 3.8. 02:43.580 --> 02:48.830 For the third grade, Emily is a top grade student who has a 4.0. 02:48.860 --> 02:56.720 For the fourth grade student, the student is James and the level is 3.9. 02:58.140 --> 03:03.990 But if you take a look at the result, the values are wrapped inside the optional right? 03:03.990 --> 03:06.420 So there is a way we can avoid this. 03:07.470 --> 03:10.020 I'm going to implement the same thing here. 03:11.880 --> 03:17.670 And I'm going to wrap this whole max by using collecting. 03:17.670 --> 03:21.180 And then there is a method called collecting. 03:21.180 --> 03:25.950 And then and I'm going to pass this as an input to this one. 03:26.130 --> 03:32.490 And then what we are going to do, we are going to use optional. 03:33.420 --> 03:36.420 Let me put this below so that the code will be clear. 03:36.450 --> 03:37.470 Optional colon. 03:37.470 --> 03:37.770 Colon. 03:37.770 --> 03:38.370 Get. 03:38.610 --> 03:43.440 So what this is going to do, this is going to wrapping it here. 03:43.440 --> 03:44.790 That is not right. 03:45.930 --> 03:47.430 Then let's put it here. 03:49.370 --> 03:52.790 And then this is going to return a student. 03:53.710 --> 03:54.670 The place of this. 03:54.670 --> 03:55.600 Let's give it a name. 03:55.600 --> 04:02.560 So what we are doing is instead of wrapping the student inside the optional this collecting, and then 04:02.560 --> 04:08.470 what it is going to do, this is going to get the student of the student is available and then assign 04:08.470 --> 04:09.750 that as an value. 04:09.760 --> 04:16.360 So what I'm going to do, I'm going to copy this and then put it here and then I'm going to print optional 04:16.360 --> 04:16.900 one. 04:17.690 --> 04:22.130 When I come on this one, Let's validate this by running this example. 04:23.260 --> 04:23.900 There you go. 04:23.920 --> 04:29.680 It removed the optional object and then it gave you the actual object itself. 04:30.410 --> 04:33.650 Now we have coded the top use case. 04:33.650 --> 04:36.530 Let's go ahead and code the least use case. 04:37.390 --> 04:39.670 I'm going to just copy and paste it here. 04:40.000 --> 04:49.090 The example is the same here it is going to be calculate least GPA in the place of max by I'm going 04:49.090 --> 04:50.500 to use min by. 04:51.520 --> 04:52.860 Because of Maxpay. 04:52.870 --> 04:53.950 I'm going to use Min Buy. 04:54.580 --> 04:55.480 That's it. 04:55.510 --> 04:59.680 If I run it, it is going to give you the student with who has the least GPA. 04:59.770 --> 05:00.970 If you take a look at it. 05:02.310 --> 05:03.000 Here. 05:03.120 --> 05:04.710 We are still printing this. 05:05.160 --> 05:06.420 I'm going to come on this. 05:06.450 --> 05:08.370 I'm going to call this method, right? 05:08.490 --> 05:11.040 I'm still calling the top here. 05:11.850 --> 05:14.370 That's the reason why you have the top over there. 05:14.370 --> 05:15.570 But we don't want that. 05:15.570 --> 05:17.460 We want the least student. 05:17.490 --> 05:23.430 If I run this, it is going to print the student who has the least GPA in each and every grade. 05:23.460 --> 05:28.260 So for the second grade, Adam is a student who has the least GPA as. 05:29.170 --> 05:30.100 3.6. 05:30.100 --> 05:33.280 And for the third grade it is like it is day. 05:33.310 --> 05:36.900 Who has the GPA as 3.9 for the fourth grade? 05:36.910 --> 05:38.500 This grade level is. 05:39.820 --> 05:43.650 Four and the 3.5 on the student name is Sofia. 05:43.870 --> 05:48.280 So this is all about grouping the students based on their grade level. 05:48.310 --> 05:54.400 Basically, we have coded the use case of grouping the grouping by along with the min by. 05:54.520 --> 05:57.310 And then we have integrated the collecting. 05:57.310 --> 06:02.300 And then also in this use case with this, we came to the end of this tutorial. 06:02.320 --> 06:03.520 Thank you for watching.