Error for get_class_average function


#1



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

The error message is :: "Oops, try again. get_class_average([alice]) resulted in an error: string indices must be integers, not str"

I expect the function to work fine.

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)
    if len(numbers)>0:
       avg=total/len(numbers)
    return avg
#categorical average function
def get_average(student):
    homework=average(student["homework"])
    hw_wt=homework*0.1
    quizzes=average(student["quizzes"])
    qz_wt=quizzes*0.3
    tests=average(student["tests"])
    t_wt=tests*0.6
    return (hw_wt+qz_wt+t_wt)
#grade determining function
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"

print "The grade of Lloyd: "
get_letter_grade(get_average(lloyd))
#class average determining function
def get_class_average(students):
    results=[]
    classlist=['lloyd','alice','tyler']
    for student in classlist:
        avg=get_average(student)
        results.append(avg)
    for s in range(0,len(classlist)):
        averg=average(s)
    return averg


#2

@bitplayer19578,
First of all you have to understand the working of a function
as it can take a parameter
and when you call the function
you are providing a so-called argument

the FUNCTION talk

def myFunc( param1, param2):
    # Begin of =myFunc= FUNCTION-BODY
    # this =myFunc= function- has 2 PARAMETERS param1 and param2
    # param1 and param2 PARAMETERS are used 
    # as -local- VARIABLES throughout the =myFunc= FUNCTION-BODY
    print( param1 + " and " + param2 )
    #End of =myFunc= FUNCTION-BODY

If you want to call/execute the myFunc function
you will have to add a pair of parentheses to myFunc
like
myFunc()
As the myFunc function was defined
as having 2 parameters
you have to provide 2 arguments
in our case 2 string VALUES "Alena" and "Lauren"
like
myFunc("Alena","Lauren")

some quotes from the outer-world:

**argument is the value/variable/reference being passed in,
parameter is the receiving variable used within the function/block**

OR

**"parameters" are called "formal parameters",
while "arguments" are called "actual parameters".**

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++ function with 1 parameter using return-statement

def myFunction( param1 ):
    # //Begin of =myFunction= FUNCTION-BODY
    # //=myFunction= function has 1 PARAMETER param1
    # //this param1 PARAMETER is used as a -local- VARIABLE
    # //throughout the =myFunction= FUNCTION-BODY
    return param1;
    # //End of FUNCTION-BODY

You have defined a myFunction function
which takes 1 parameter param1
this param1 parameter is used
as a variable throughout the =myFunction= FUNCTION-BODY.

If you want to call/execute this myFunction function
and this myFunction function was defined
as having 1 parameter param1
you will have to provide 1 argument
in our case a "number VALUE" 4
myFunction( 4 )

some quotes from the outer-world:

**argument is the value/variable/reference being passed in,
parameter is the receiving variable used within the function/block**

OR

**"parameters" are called "formal parameters",
while "arguments" are called "actual parameters".**

============================================

As you are using the return-statement in your myFunction function
you will only get a return-value no-display.
You can however capture this return-value in a variable
and then use the print-method to do a display.

theResult = myFunction( 4 )
print theResult

OR directly

print myFunction( 4 )

#3

@bitplayer19578,
Now if you define the get_class_average() function
like

def get_class_average(students):

you have defined the get_class_average() function as taking 1 parameter students

This students parameter
will be used as a =local= variable in the FUNCTION-BODY ( in the code-block of the function)
thus

def get_class_average(students):
    # Begin of FUNCTION-BOY
    # PARAMETER student is a =local= VARIABLE
    #
    tot_avg = 0
    list_result = []
    for student in students:
        # we expect the =students= VARIABLE to be a =list=
        # and we expect each =list-Element= to be a =dictionary=
        new_avg = get_average(student)
        # tot_avg = tot_avg + new_avg
        # or in shorthand
        tot_avg += new_avg
        list_result.append(new_avg)
    # end of FOR-loop
    # calculate the real average
    list_real_avg = sum(list_result) / len(students)
    tot_real_avg = tot_avg / len(students)
    print("{0} {1}".format(tot_real_avg,tot_real_avg))
    return tot_real_avg

As you have defined 3 variables lloyd, alice and tyler
to each of which you assigned a dictionary Value
and the get_class_average() function expects you to use a =list= of =dictionaties=
you could call the get_class_average() function
like

print get_class_average([lloyd,alice])