8. Part of Whole


#1



https://www.codecademy.com/courses/python-beginner-en-qzsCL/1/4?curriculum_id=4f89dab3d788890003000096


If I define the results list before the functions it gives erroneous results.


lloyd = {
    "name": "Lloyd",
    "homework": [90.0, 97.0, 75.0, 92.0],
    "quizzes": [88.0, 40.0, 94.0],
    "tests": [75.0, 90.0]
}
alice = {
    "name": "Alice",
    "homework": [100.0, 92.0, 98.0, 100.0],
    "quizzes": [82.0, 83.0, 91.0],
    "tests": [89.0, 97.0]
}
tyler = {
    "name": "Tyler",
    "homework": [0.0, 87.0, 75.0, 22.0],
    "quizzes": [0.0, 75.0, 78.0],
    "tests": [100.0, 100.0]
}
results = []

def average(numbers):
    total = float(sum(numbers))
    total = total/len(numbers)
    return total

def get_average(student):
    homework = average(student["homework"])
    quizzes = average(student["quizzes"])
    tests = average(student["tests"])
    
    return (0.1*homework) + (0.3*quizzes) + (0.6*tests)
    
def get_letter_grade(score):
    if score >= 90:
        return "A"
    elif score >= 80:
        return "B"
    elif score >= 70:
        return "C"
    elif score >= 60:
        return "D"
    else :
        return "F"

def get_class_average(students):
    
    for student in students:
        avg = get_average(student)
        results.append(avg)
    return average(results)
    
print get_letter_grade(get_average(lloyd))

https://www.codecademy.com/en/courses/python-beginner-en-qzsCL/1/4?curriculum_id=4f89dab3d788890003000096


#2

you should define the results list inside the function before the for loop


#3

Why is that necessary? As in it's defined globally so shouldn't be a problem I guess.


#4

it will be a problem when you call the function multiply times:

results = []

def get_class_average(students):
    
    for student in students:
        avg = get_average(student)
        results.append(avg)
    return average(results)

print get_class_average([lloyd])
print get_class_average([lloyed, alice])
print get_class_average([lloyed, alice, tyler])

given now the results list will maintain the result from earlier function calls, which causes incorrect class averages


#5

But why giving an error the first time?


#6

the first time, where does the refer to?


#7

Well I was asking while executing for first time why would it show an error?


#8

because the exercise verifies your code works correctly by calling the function multiply times


#9

Thanks a lot for the help @stetim94


#10

This topic was automatically closed 7 days after the last reply. New replies are no longer allowed.