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]
}

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

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

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?

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)

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

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)

#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])``````