Diffrence between Codecademy and official Visualize Python?


#1

Hi,

(after maaaaaaaaany attemps) I ended 8/9, but I'm trying to understand this code better, so I put it to Python's visualizer (here).
At codecademy it's 'way to go!', but visualizer says something different...

My code:

    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]
}

# Add your function below!
def average(numbers):
    total = sum(numbers)
    total = float(total)
    total = total/len(numbers)
    return total
    
def get_average(student):
    homework = average(student["homework"])
    quizzes = average(student["quizzes"])
    tests = average(student["tests"])
    homework = 0.1*average(student["homework"])
    quizzes = 0.3*average(student["quizzes"])
    tests = 0.6*average(student["tests"])
    return homework+quizzes+tests
    print homework+quizzes+tests
    
def get_letter_grade(score):
    if score >= 90:
        return "A"
    if score >= 80:
        return "B"
    if score >= 70:
        return "C"
    if score >= 60:
        return "D"
    else:
        return "F"


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

print get_class_average(tyler)

After step 20 (it's executing print get_class_average(tyler)) errors occurs - in lane 28 (homework = average(student["homework"])) it calls "TypeError: string indices must be integers, not str"

Why is it different in codecademy and visualizer? I'm using P2.7.8 on it.
And how make it works?

Thanks in advance,

Szkaplerny


#2

As far as I understand, the first problem seems to be in print get_class_average(tyler). tyler is supposed to be in a list because the for loop only works with a list or dictionary.
It should look something like this:

student = [tyler]
print get_class_average(student)

Or

print get_class_average([tyler])

Also, when you use .append() there is supposed to be an argument (what you're going to append to the list) inside the parenthesis.
It should look something like this:

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

print get_class_average([tyler])

Or

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

print get_class_average([tyler])

My code:

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)) / 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):
    results = []
    for s in students:
        results.append(get_average(s))
    return average(results)

students = [lloyd, alice, tyler]
print get_class_average(students)
print get_letter_grade(get_class_average(students))

#3

Thank you a lot - Idk why I uploaded here code results.append() without argument. That was a fail.
But I didn't know about for loop - that it works only with lists or dictionaries and this was very helpful!


#4

I improved my code and have one more question.

You have:

students = [lloyd, alice, tyler]
print get_class_average(students)

And I created

students = [lloyd, alice, tyler]
print get_class_average([students])

When I type your code with my ending it calls "TypeError: list indices must be integers, not str" at step 28.
Could you tell me please why is it difference for Python and how it works?


#5

Note: I am still a student learning Python, therefore I may be wrong.

By putting the list students inside brackets you have put it inside a list. Now you have two lists (a list inside a list) and, since the for loop is needed in order to iterate through a list, two for loops are now needed (one for loop for every list).

For print get_class_average([students]) to work the function def get_class_average(students): should look something like this:

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

students = [lloyd, alice, tyler]
print get_class_average([students])