Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 00:00:00,030 --> 00:00:02,850 So now that you've gotten a taste for for loops, 2 00:00:03,120 --> 00:00:05,670 it's time to complete another challenge 3 00:00:05,880 --> 00:00:10,880 which is going to stretch you a little bit further. Head over to day 5.2 highest 4 00:00:12,060 --> 00:00:12,893 score, 5 00:00:13,350 --> 00:00:17,640 and we're going to get a list of students scores, 6 00:00:18,210 --> 00:00:20,700 and it's a list of numbers again. 7 00:00:21,390 --> 00:00:23,760 The idea is that you are going to write some code 8 00:00:24,060 --> 00:00:27,690 that's going to output the highest score in the class. 9 00:00:28,050 --> 00:00:30,150 So you're going to look through this list 10 00:00:30,420 --> 00:00:35,420 using a for loop and figure out which of the scores inside the list is the 11 00:00:36,090 --> 00:00:40,470 highest value. Now we can see pretty much at a glance that inside this list, 12 00:00:40,500 --> 00:00:44,670 91 is the highest. But remember that when you test your code, 13 00:00:45,090 --> 00:00:49,200 you won't be able to see the input. So you won't be able to cheat that way. 14 00:00:49,650 --> 00:00:54,480 Instead, you have to do this using code. Now, just as in the last lesson 15 00:00:54,480 --> 00:00:58,560 I mentioned that Python has some pretty useful functions that help us do a lot 16 00:00:58,560 --> 00:01:01,890 of these commonly needed things very easily 17 00:01:02,100 --> 00:01:05,580 such as the sum and the len functions, well, in this case, 18 00:01:05,910 --> 00:01:08,700 there's actually something called the max function. 19 00:01:09,240 --> 00:01:11,400 So if we pass a list, 20 00:01:11,460 --> 00:01:15,810 let's say the student_scores list into a max function 21 00:01:16,290 --> 00:01:21,290 and then I go ahead and print out the maximum value from my list of student_ 22 00:01:22,590 --> 00:01:26,700 scores. So let's run this code and I'm going to use the example input, 23 00:01:26,970 --> 00:01:31,500 so a bunch of numbers separated by a space, and hit enter, 24 00:01:31,920 --> 00:01:35,190 and you can see it tells me that 91 is the highest value. 25 00:01:35,760 --> 00:01:38,340 Now there's also the min function 26 00:01:38,820 --> 00:01:43,560 which basically will give me the lowest value inside a particular list, 27 00:01:43,830 --> 00:01:47,850 which in this case is 55, but that's too easy. 28 00:01:48,330 --> 00:01:52,530 I don't want you to use the max or the min functions. Instead, 29 00:01:52,740 --> 00:01:57,210 you have to use what you've learned about for loops to replicate the underlying 30 00:01:57,210 --> 00:02:00,150 functionality of this max function. 31 00:02:00,600 --> 00:02:04,530 Because people tend to use Python to do a lot of data manipulation, 32 00:02:04,710 --> 00:02:07,020 to do a lot of mathematical calculations. 33 00:02:07,260 --> 00:02:09,690 It has a lot of these convenient functions for you. 34 00:02:10,170 --> 00:02:14,130 But let's say you moved to a different language and you work on something else, 35 00:02:14,220 --> 00:02:15,540 then these might not exist. 36 00:02:15,900 --> 00:02:20,070 So understanding the underlying logic and being able to write out the code 37 00:02:20,340 --> 00:02:24,780 using things that every programming language has like the for loop will mean 38 00:02:24,780 --> 00:02:28,440 that you will become a much, much better programmer in the process. 39 00:02:28,980 --> 00:02:33,980 So try and replicate the functionality of the max function and the output should 40 00:02:34,470 --> 00:02:35,340 have the words 41 00:02:35,580 --> 00:02:40,580 The highest score in the class is : and then a space and then the actual max 42 00:02:42,900 --> 00:02:47,010 value. So this is what should happen. Pause the video now, 43 00:02:47,040 --> 00:02:51,510 and have a think about how you would write your code in order to get hold of the 44 00:02:51,510 --> 00:02:53,130 maximum value from a list. 45 00:02:57,990 --> 00:03:01,480 All right. So did you manage to complete this challenge? If not, 46 00:03:01,600 --> 00:03:05,470 and if you want to see how I do it, then continue watching along. 47 00:03:06,610 --> 00:03:10,960 The first thing we want to do is we probably want to get a hold of each of the 48 00:03:10,960 --> 00:03:14,140 scores inside our list of student scores. 49 00:03:14,560 --> 00:03:18,520 So I'm going to write something like for score in student_scores, 50 00:03:19,060 --> 00:03:19,630 so again, 51 00:03:19,630 --> 00:03:24,520 keeping that convention of singular from plural. Now, 52 00:03:24,610 --> 00:03:27,370 inside the loop, what can I do? Now 53 00:03:27,370 --> 00:03:30,280 let's say I had a variable called the highest_score, 54 00:03:30,820 --> 00:03:35,800 and I'm going to start it off as zero. And then inside my loop, 55 00:03:35,950 --> 00:03:40,950 I can use an if statement to check, well is the current score that I'm looping 56 00:03:42,220 --> 00:03:46,540 through greater than the highest score that I've got. 57 00:03:47,200 --> 00:03:51,760 Well then if so, that means that this current score should actually be the 58 00:03:51,760 --> 00:03:52,593 highest score. 59 00:03:52,960 --> 00:03:57,550 So I can set my highest_score to equal, 60 00:03:57,580 --> 00:04:01,210 single equals mean assign, double equals mean checking, remember? 61 00:04:01,900 --> 00:04:06,900 And this loop will continue running until I've checked through all the scores 62 00:04:08,110 --> 00:04:09,910 inside my student_scores, 63 00:04:10,360 --> 00:04:13,780 and I've got the highest score stored inside this variable. 64 00:04:14,290 --> 00:04:18,190 So now I can go ahead and print the sentence; 65 00:04:19,090 --> 00:04:22,930 The highest score is this particular value. 66 00:04:22,990 --> 00:04:27,990 So I'm going to use an f-string to insert my highest_score variable inside here. 67 00:04:30,760 --> 00:04:35,530 And if I run my code and use this example input, then you can see 68 00:04:35,530 --> 00:04:38,410 it tells me the high score in the class is 91, 69 00:04:38,860 --> 00:04:42,790 which matches exactly with the example output. Now, 70 00:04:42,820 --> 00:04:46,360 if you're at all confused about how this code works, 71 00:04:46,660 --> 00:04:50,290 then I recommend again, pasting it into Thonny like this. 72 00:04:50,320 --> 00:04:55,320 So you've got a list of scores and then you've got the code in the solution and 73 00:04:55,450 --> 00:04:56,350 click on debug. 74 00:04:56,560 --> 00:05:01,560 And you can see how we actually step through each of the stages where we start 75 00:05:02,830 --> 00:05:07,240 off with a highest score being equal to zero, so that's where it is, 76 00:05:08,320 --> 00:05:13,320 and then we continue into the loop where we go through each of the scores inside 77 00:05:13,930 --> 00:05:17,890 the student_scores, so the first one is going to be 78. 78 00:05:18,490 --> 00:05:22,960 So now we've got this variable score which is tied to the value of 78. 79 00:05:23,470 --> 00:05:27,100 And then we go and check if the score, 80 00:05:27,640 --> 00:05:32,560 which is 78, is greater than the highest score, which is zero. Well, 81 00:05:32,560 --> 00:05:36,070 that's obviously true, right? So if that's true, 82 00:05:36,070 --> 00:05:38,230 then it's going to carry out the next line of code, 83 00:05:38,620 --> 00:05:42,220 which is that the highest score is now equal to score. 84 00:05:42,910 --> 00:05:47,910 So now notice how this highest_score variable is going to update to the first 85 00:05:49,150 --> 00:05:51,940 value because 78 is greater than zero. 86 00:05:52,480 --> 00:05:55,990 Now we go back to the start of the loop and we go to the next value, 87 00:05:55,990 --> 00:06:00,990 65. And 65 is now checked against the highest score. Is 65 greater than 78? 88 00:06:04,430 --> 00:06:07,340 Well, no, that's not true. So this is false. 89 00:06:07,640 --> 00:06:12,640 And so the highest score is left alone. And we continue back to the next value. 90 00:06:13,130 --> 00:06:18,130 So now our score is equal to 89 and our highest_score is still equal to 78. Is 89 91 00:06:20,750 --> 00:06:22,730 greater than 78? Yes. 92 00:06:22,790 --> 00:06:27,290 So now we reset the highest_score to the new value, 93 00:06:27,620 --> 00:06:28,730 which is 89. 94 00:06:29,030 --> 00:06:34,030 And it continues this loop until it gets to the end and it's found the highest 95 00:06:34,220 --> 00:06:37,430 value and it prints it out into the console. 96 00:06:38,240 --> 00:06:42,410 Play around with the debug and step through each of the stages to see how it 97 00:06:42,410 --> 00:06:46,340 works and compare it with what's happening with each of the variables on the 98 00:06:46,340 --> 00:06:47,810 right. This is a really, 99 00:06:47,810 --> 00:06:51,620 really useful way of wrapping your head around all of this complex, 100 00:06:51,620 --> 00:06:56,480 looping and conditionals. And once you've understood everything that's going on, 101 00:06:56,660 --> 00:07:00,830 then you can continue to the next lesson where we're going to talk about another 102 00:07:00,830 --> 00:07:05,030 type of for loop, the for loop using a range operator. 103 00:07:05,210 --> 00:07:08,000 So for all of that and more, I'll see you in the next lesson. 10223