How to make automatic grader with Python3

Question

I'm a beginner for coding. I'm struggling to make student grader which each student names would be corresponded to each grade averages and show total average score among students. This is my code :

Ken = [5,8,9]
Hiro = [10,11,20]
Nick = [20,20,20]

list1 = [Ken,Hiro,Nick]

total_average = 0
for j in list1:
   x = 0
   count = 0
   for i in j:
       x += i
       count += 1

   average = x / count
   print (round(average,2))
   total_average += average

final_average = total_average / len(list1)
print (round(final_average,2))

and result is :

7.33
13.67
20.0
13.67

However, I actually want to make code which returns like :

13.67, {'Ken': 13.67, 'Hiro': 20.0, 'Nick': 13.67}

How could I express like this ?

It would be greatly appreciated if you could explain the details !!

Answer 1

I would suggest another approach altogether. First, you store your names and grades in a dictionary:

grades = {'Ken': [5,8,9], 'Hiro': [10,11,20], 'Nick': [20,20,20]}

Then, you loop over the dictionary and compute the average for each student and prepare to compute the global average:

averages = {}
sum_of_grades, number_of_grades = 0, 0
for name, marks in grades.items():
    averages[name] = sum(marks) / len(marks) # simple arithmetic average
    sum_of_grades += sum(marks)
    number_of_grades += len(marks)

Finally, you compute the global average:

final_average = sum_of_grades / number_of_grades

Here is the complete code, where the computations are encapsulated in a function:

grades = {'Ken': [5,8,9], 'Hiro': [10,11,20], 'Nick': [20,20,20]}

def compute_averages(grades):
    averages = {}
    sum_of_grades, number_of_grades = 0, 0
    for name, marks in grades.items():
        averages[name] = sum(marks) / len(marks)
        sum_of_grades += sum(marks)
        number_of_grades += len(marks)
    final_average = sum_of_grades / number_of_grades

    return averages, final_average

averages, final_average = compute_averages(grades)
for name, avg in averages.items():
    print(name, round(avg, 2))
print('Final average', round(final_average, 2))

Answer 2

Try using dictionary instead of lists. Initialize the dictionary: students = {'Hiro': 0, 'Ken': 0, 'Nick': 0}

Then assign values based on the computed average: students = {'Hiro': 20.0, 'Ken': 13.67, 'Nick': 13.67}

print(students)