1 00:00:00,600 --> 00:00:03,060 In this exercise, you are going to create 2 00:00:03,060 --> 00:00:07,980 a program that grades a student's test scores. 3 00:00:07,980 --> 00:00:12,180 You'll see on lines 1 to 7, that we've got a dictionary, 4 00:00:12,180 --> 00:00:14,310 and it's called student_scores. 5 00:00:14,310 --> 00:00:15,390 Inside the dictionary, 6 00:00:15,390 --> 00:00:18,120 the keys are the names of our students, 7 00:00:18,120 --> 00:00:21,450 and the values are their test scores. 8 00:00:21,450 --> 00:00:24,810 What you are going to do is using a for loop to loop 9 00:00:24,810 --> 00:00:27,600 through the dictionary, you're going to write a program 10 00:00:27,600 --> 00:00:31,320 that can interpret each student's scores 11 00:00:31,320 --> 00:00:36,320 and create a new dictionary called student_grades 12 00:00:36,390 --> 00:00:40,650 and in this dictionary, you have the student names matching 13 00:00:40,650 --> 00:00:43,110 with their corresponding grades. 14 00:00:43,110 --> 00:00:46,050 If you take a look inside the Description pane, 15 00:00:46,050 --> 00:00:50,580 you will see the scores and their corresponding grades. 16 00:00:50,580 --> 00:00:54,330 So for example, a score of 91 to 100 is interpreted 17 00:00:54,330 --> 00:00:58,680 as Outstanding, 81 to 90 is Exceeds Expectations, 18 00:00:58,680 --> 00:01:00,420 and so on and so forth. 19 00:01:00,420 --> 00:01:04,470 Take a look at the Expected Output and see if you can 20 00:01:04,470 --> 00:01:08,310 figure out how to use a loop on a dictionary 21 00:01:08,310 --> 00:01:12,720 in order to make your program work as expected. 22 00:01:12,720 --> 00:01:13,570 Give it a go now. 23 00:01:21,450 --> 00:01:24,900 The first thing I'm going to do is to create a dictionary 24 00:01:24,900 --> 00:01:26,610 called student_grades 25 00:01:26,610 --> 00:01:30,060 and simply have it as an empty dictionary { }. 26 00:01:30,060 --> 00:01:33,243 This is what we're going to fill up using our program. 27 00:01:34,290 --> 00:01:37,860 Next, I'm going to create a for loop that loops through 28 00:01:37,860 --> 00:01:42,240 the dictionary of student_scores so that I can get hold 29 00:01:42,240 --> 00:01:45,333 of each of the keys in that dictionary one by one. 30 00:01:46,320 --> 00:01:49,110 In order to access that student_score, 31 00:01:49,110 --> 00:01:52,590 I have to use the key on the student_scores dictionary. 32 00:01:52,590 --> 00:01:57,270 So exact line of code looks like line 14 where the score, 33 00:01:57,270 --> 00:01:59,640 the variable that I'm interested in storing 34 00:01:59,640 --> 00:02:01,410 is equal to student_scores, 35 00:02:01,410 --> 00:02:05,190 passing in each of the student names as the key, 36 00:02:05,190 --> 00:02:09,330 and now what the score will equal is the first time 37 00:02:09,330 --> 00:02:11,880 my loop runs, it'll equal to 81. 38 00:02:11,880 --> 00:02:13,290 Next time it'll be 78. 39 00:02:13,290 --> 00:02:16,023 Next time it'll be 99, and so on and so forth. 40 00:02:17,430 --> 00:02:19,950 Now comes the easier part where I have my if, 41 00:02:19,950 --> 00:02:23,730 elif, else statements, and I simply use the criteria 42 00:02:23,730 --> 00:02:28,320 that's in the Description pane to determine how each score 43 00:02:28,320 --> 00:02:29,820 is going to be interpreted. 44 00:02:29,820 --> 00:02:32,340 So if the score is greater than 90, 45 00:02:32,340 --> 00:02:34,920 then I can take the student_grades, 46 00:02:34,920 --> 00:02:37,680 which is our empty dictionary, empty for now, 47 00:02:37,680 --> 00:02:41,340 and then use the square brackets [ ] to assign the student, 48 00:02:41,340 --> 00:02:43,980 which is what we're looping on at the moment. 49 00:02:43,980 --> 00:02:46,500 That's going to be the name of the student, 50 00:02:46,500 --> 00:02:50,790 and set it to equal a value, which is going to be the grade. 51 00:02:50,790 --> 00:02:53,940 And I can do that if the score is greater than 80 52 00:02:53,940 --> 00:02:56,280 and if the score is greater than 70. 53 00:02:56,280 --> 00:02:59,940 And remember, because the way that if, elif, else statements work, 54 00:02:59,940 --> 00:03:01,980 is they work like a waterfall. 55 00:03:01,980 --> 00:03:03,570 So if the first one is false, 56 00:03:03,570 --> 00:03:05,070 then it goes to the second one. 57 00:03:05,070 --> 00:03:08,220 So even though we're only checking on line 17, 58 00:03:08,220 --> 00:03:10,620 that elif score is greater than 80 59 00:03:10,620 --> 00:03:14,070 because the first one already went into the elif 60 00:03:14,070 --> 00:03:18,210 that means the first condition on line 15 is already False. 61 00:03:18,210 --> 00:03:22,500 So that basically means that the score that we are assigning 62 00:03:22,500 --> 00:03:27,500 exceeds expectations on 18 is between 80 and 90. 63 00:03:28,440 --> 00:03:30,390 Now, the way that dictionaries work with the key 64 00:03:30,390 --> 00:03:32,550 and the value and how you access a value 65 00:03:32,550 --> 00:03:35,490 through the key can be a little bit mysterious 66 00:03:35,490 --> 00:03:37,140 but if you use print statements 67 00:03:37,140 --> 00:03:41,880 and evaluate what your beliefs and reality and compare them 68 00:03:41,880 --> 00:03:43,110 then you should be able to get 69 00:03:43,110 --> 00:03:45,810 to a point where you can solve the puzzle and figure out 70 00:03:45,810 --> 00:03:48,540 how to make the program do what you want it to. 71 00:03:48,540 --> 00:03:50,400 So if you needed to make any fixes now, 72 00:03:50,400 --> 00:03:51,450 go ahead and do that.