Part of a while


#1

I've got this...
get_class_average([alice]) resulted in an error: unsupported operand type(s) for +: 'int' and 'NoneType'

My code's below

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 = 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"])
    score = 0.1 * homework + 0.3 * quizzes + 0.6 * tests
    print score
    
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):
    results = []
    for student in students:
        get_average(student)
        results.append(get_average(student))
        return average(results)

Part of a Whole
#2

lets add a function call so we can see the interpreter error:

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

hm... somehow our results list contains None, rather then alice her grade, lets look at get_average why this happened:

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

no return keyword in get_average, so the score isn't returned. By default function returns None, which is now being appended to list, this is not what we want in our list


#3

Thank you very much!
Everything is working :smiley:


#4