1 00:00:00,210 --> 00:00:03,900 All right. So hopefully everything we've learned in the last lesson made sense, 2 00:00:04,230 --> 00:00:08,670 and you're ready to put your knowledge to the test by completing the first 3 00:00:08,670 --> 00:00:09,750 coding challenge today. 4 00:00:10,410 --> 00:00:13,410 And what you're going to be building is a grading program. 5 00:00:13,650 --> 00:00:17,610 So if you take a look at the day 9.1 grading program 6 00:00:17,970 --> 00:00:21,270 Repl.it coding exercise, you'll see that to begin, 7 00:00:21,330 --> 00:00:26,330 I've already created a dictionary with a bunch of student names and their test 8 00:00:26,970 --> 00:00:28,740 scores. Now, 9 00:00:28,770 --> 00:00:32,430 without changing any of the code above here or below here, 10 00:00:32,850 --> 00:00:37,850 I want you to write a program that will be able to convert these scores into a 11 00:00:38,550 --> 00:00:43,170 grade. So the grading criteria is over here in the instructions. 12 00:00:43,590 --> 00:00:46,590 So if the student's scores above 91, 13 00:00:46,980 --> 00:00:51,750 then they'll get the grade outstanding. If they score above 81, 14 00:00:51,750 --> 00:00:54,510 they get exceeds expectations and then acceptable. 15 00:00:54,840 --> 00:00:58,980 And then finally everybody's scoring 70 or a lower gets the fail grade. 16 00:00:59,790 --> 00:01:00,623 Essentially, 17 00:01:00,720 --> 00:01:04,800 what you're going to be doing is creating an empty dictionary from scratch 18 00:01:05,100 --> 00:01:06,960 which is going to be called student_grades. 19 00:01:07,440 --> 00:01:12,440 And you're going to write some code so that each of the students are represented 20 00:01:12,870 --> 00:01:14,490 inside this new dictionary. 21 00:01:14,970 --> 00:01:19,260 And instead of having scores as the value's in that dictionary, 22 00:01:19,530 --> 00:01:23,940 you are going to have the grades that correspond to the scores that they got. 23 00:01:24,540 --> 00:01:28,320 Have a read through the instructions and the hints if you need some help, 24 00:01:28,710 --> 00:01:32,460 but once you're ready, go ahead and pause the video and give this a go. 25 00:01:32,660 --> 00:01:37,660 [inaudible] 26 00:01:39,050 --> 00:01:42,440 All right. So to begin, let's first tackle this to-do 1. 27 00:01:42,950 --> 00:01:47,300 Let's create a new empty dictionary called student_grades. 28 00:01:48,560 --> 00:01:53,240 And the student_grades has to be spelled exactly the same as you see here, 29 00:01:53,510 --> 00:01:55,970 because otherwise this print statement will not work. 30 00:01:56,570 --> 00:01:58,730 The student_grades is gonna be an empty dictionary, 31 00:01:58,760 --> 00:02:01,610 which if you remember from the last lesson, we said 32 00:02:01,640 --> 00:02:05,480 it looks like this with two curly braces and nothing inside. 33 00:02:06,230 --> 00:02:08,780 Now let's move on to todo number 2. 34 00:02:09,020 --> 00:02:14,020 So we're going to write some code below so that we actually add the grades to 35 00:02:14,570 --> 00:02:16,850 this student grades dictionary. 36 00:02:17,330 --> 00:02:21,710 And we of course can get those grades by looking at each of the student's 37 00:02:21,740 --> 00:02:25,460 scores. How can we do this? Well, 38 00:02:25,460 --> 00:02:30,050 we're probably going to need a for loop because there's lots of items in this 39 00:02:30,050 --> 00:02:34,730 dictionary. Let's go ahead and loop through this student_scores dictionary, 40 00:02:35,270 --> 00:02:39,500 and I'm going to call each of the items the student, 41 00:02:39,740 --> 00:02:44,740 because remember when we have a for loop looping through a dictionary like we 42 00:02:45,320 --> 00:02:46,250 are doing here, 43 00:02:46,910 --> 00:02:51,860 each of the items that gets picked out is actually the key rather than the whole 44 00:02:51,860 --> 00:02:55,340 item. So again, we talked about this in the last lesson, 45 00:02:55,850 --> 00:03:00,670 but hopefully, this should really make it clear. But even if you didn't know, 46 00:03:00,910 --> 00:03:03,670 you could always of course just print it, right? 47 00:03:03,760 --> 00:03:07,090 So if we go ahead and use the for loop and print it, 48 00:03:07,090 --> 00:03:12,090 you can see we get all of the keys from this dictionary when we're looping 49 00:03:13,780 --> 00:03:17,080 through it. So for each of the students, 50 00:03:17,110 --> 00:03:19,210 we want to get hold of their score. 51 00:03:19,630 --> 00:03:23,200 We can calculate the score by getting hold of the value 52 00:03:23,440 --> 00:03:27,460 using this key from this dictionary. And to do that, 53 00:03:27,640 --> 00:03:30,520 if you remember, is tapping in to the dictionary, 54 00:03:31,000 --> 00:03:35,320 adding a set of square brackets and then giving it the key. So in this case, 55 00:03:35,320 --> 00:03:40,210 it's going to be each of the student names. And once we've got a hold of the 56 00:03:40,210 --> 00:03:43,570 score, well then we can use our if statement to check well 57 00:03:43,840 --> 00:03:46,480 if the score is greater than 90, 58 00:03:47,170 --> 00:03:48,940 so anything above 90, 59 00:03:49,270 --> 00:03:53,020 then that means they're going to end up with outstanding. 60 00:03:53,530 --> 00:03:58,530 Now, this is the part where we add a new entry to this student_grades dictionary. 61 00:03:59,230 --> 00:04:04,000 So let's tap into the dictionary, use a set of square brackets again 62 00:04:04,060 --> 00:04:06,640 to give it a key. And the key, 63 00:04:06,640 --> 00:04:10,360 of course, should still be the student name which comes from here, 64 00:04:10,900 --> 00:04:12,850 which is going to be the same as this. 65 00:04:13,360 --> 00:04:17,770 Then we can add a equal sign and followed by the value 66 00:04:18,220 --> 00:04:20,380 which is going to be outstanding. 67 00:04:21,670 --> 00:04:25,780 So now we can repeat this process for the rest of these grades. 68 00:04:26,130 --> 00:04:26,963 Yeah. 69 00:04:29,130 --> 00:04:34,020 Everybody who scored above 80 but not above 90, so remember that this 70 00:04:34,020 --> 00:04:38,640 if statement once triggered, will skip all of the rest of the elif statements. 71 00:04:41,700 --> 00:04:46,290 And then if they scored above 70, they would get acceptable. And finally, 72 00:04:46,290 --> 00:04:49,740 for everybody else, which means they scored lower than 70, 73 00:04:50,100 --> 00:04:52,710 then they're going to end up with a fail grade. 74 00:04:53,700 --> 00:04:58,590 Now it's really important that if you want the test to pass that each of these 75 00:04:58,590 --> 00:05:02,430 strings has to match what you see over here exactly. 76 00:05:03,120 --> 00:05:07,320 Now that we've done all of this hard work, manipulating our dictionary, 77 00:05:07,710 --> 00:05:12,210 it's time to actually go ahead and run our code and see what we get. 78 00:05:12,840 --> 00:05:15,060 So now our code has converted 79 00:05:15,090 --> 00:05:18,300 each of these scores to the corresponding grade. 80 00:05:18,750 --> 00:05:23,750 Harry gets exceeds expectations because his score is between 81 and 90, Ron gets 81 00:05:25,320 --> 00:05:29,340 acceptable because it's between 70 and 80, and so on and so forth. 82 00:05:30,300 --> 00:05:31,770 Now, did you manage to get it right, 83 00:05:32,220 --> 00:05:35,700 or did you have any problems working with dictionaries? Now, 84 00:05:35,760 --> 00:05:37,290 if you go beyond this lesson 85 00:05:37,320 --> 00:05:41,400 I'm going to assume that you are comfortable with editing dictionaries, 86 00:05:41,430 --> 00:05:43,500 adding to it, creating new ones. 87 00:05:43,980 --> 00:05:47,880 So if you are not yet fully there, then I recommend just going back to the last 88 00:05:47,880 --> 00:05:49,890 lesson, just reviewing it once more. 89 00:05:50,910 --> 00:05:53,280 Once you've done that, head over to the next lesson 90 00:05:53,490 --> 00:05:58,230 and we're going to talk more about nesting in dictionaries and lists. For all of that 91 00:05:58,470 --> 00:05:59,820 and more, I'll see you there.