# 8. part of a whole

#1

i'm a bit confused as to why this code doesn't work? (the error message says: get_class_average(alice) should return a number)

shouldn't we loop over the class_list to get the average grade for each student? /:

thank you so much!

``````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]
}

def average(numbers):
total = sum(numbers)
total = float(total)

def get_average(student):
homework = average(student["homework"])
quizzes = average(student["quizzes"])
tests = average(student["tests"])
return homework * 0.1 + quizzes * 0.3 + tests * 0.6

if score >= 90:
return "A"
elif score >= 80:
return "B"
elif score >= 70:
return "C"
elif score >= 60:
return "D"
else:
return "F"

students = [lloyd, alice, tyler]

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

8. Part of the Whole
#2

here:

``return results.append(get_average(student))``

a function ends the moment a return keyword is reached, the loop is used to append each student average grade to the results list, so no need to use return here

#3

thank you so much! so when should we use the "return" keywords in general? (":

do you have any idea why the error now reflects as: "Oops, try again. get_class_average([alice, lloyd]) returned 91.15 instead of 85.85 as expected"

``````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]
}

def average(numbers):
total = sum(numbers)
total = float(total)
def get_average(student):
homework = average(student["homework"])
quizzes = average(student["quizzes"])
tests = average(student["tests"])
return homework * 0.1 + quizzes * 0.3 + tests * 0.6
if score >= 90:
return "A"
elif score >= 80:
return "B"
elif score >= 70:
return "C"
elif score >= 60:
return "D"
else:
return "F"
students = [lloyd, alice, tyler]
def get_class_average(students):
results = []
for student in students:
results.append(get_average(student))
return average(results)``````

#4

by default, when a function ends, it return None. By using the `return` keyword, we can let the function return something different then None.

We determined the function ends the moment a return keyword is reached, so your loop now only makes one itration

#5

thank you!!! i get it now!!!! (": so the return average(results) needs to be outside the "for" function?

#6

outside the for loop, yes

#7

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