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Python Python Basics (Retired) Putting the "Fun" Back in "Function" Functions

Milagros Roman
Milagros Roman
1,228 Points

Could you please help me to resolve this error? Bummer! TypeError: 'int' object is not iterable

functions.py
# add_list([1, 2, 3]) should return 6
# summarize([1, 2, 3]) should return "The sum of [1, 2, 3] is 6."
# Note: both functions will only take *one* argument each.
added_list = list()
summarize = 0

def add_list(num):
  added_list.append(num) 

def summarize(num):
  summarize = summarize + add_list[num]

for num in 4:
  add_list(num)
  summarize(num)

print(summarize)   

[edit formating -cf]

6 Answers

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,166 Points

Your primary error "TypeError: 'int' object is not iterable" is caused by the statement for num in 4 because the for statement operates on iterable data such as a string, list, tuple, or other object container.

What may not be clear is the structure needed to complete the challenge. When asked to "make a function", the challenge expects a function to be defined to accept certain arguments and return a value. You are not required to print or output the result. The grader program will call the defined function with test values and check the returned value against expected results.

For task 1 of this challenge, you are asked to "Make a function named add_list that takes a list. The function should then add all of the items in the list together and return the total."

The would look like:

# define function called "add_list" with one argument
def add_list(input_list):
    # initialize result
    sum = 0
    # Iterate over the input_list to sum elements
    for item in input_list:
        sum = sum + item
    # return results
    return sum

For task 2 you are asked "Now, make a function named summarize that also takes a list. It should return the string "The sum of X is Y.", replacing "X" with the string version of the list and "Y" with the sum total of the list."

# define function called "summarize" with one argument
def summarize(input_list):
    # sum elements in input_list using add_list() function
    total = add_list(input_list)
    # formated string with total: "The sum of X is Y."
    string = "The sum of {} is {}.".format(input_list, total)
    # return results
    return string

As you advance in learning Python programming you will learn to combine statements and use other common idioms.

# For example

# Accumulating to a sum
sum = sum + item
# can be replace by
sum += time

# summarize could be reduced to not-obvious-for-beginners version
def summarize(input_list):
    return "The sum of {} is {}.".format(input_list, add_list(input_list))
John Coolidge
John Coolidge
12,614 Points

Is there a reason during Python challenges I'm asked to use things like total (shown in the above explanation) that I don't ever recall seeing used in the videos thus far? If I've missed it, then that's on me, but it seems I'm asked to use python code that I've not encountered before in order to do the challenges. I'm a complete newbie so how am I to do these challenges when the videos haven't set me up with new terms/code?

Chris Freeman
Chris Freeman
Treehouse Moderator 68,166 Points

John Coolidge, there isn't anything special about total in the above example. It is merely a temporary local variable used to hold intermediate results. As shown in the second example, many statements may be combined into a single statement eliminating the use of the local variable total.

Breaking up code into multiple statements can help improve readability. In in first example I wanted to explicitly call add_list() on a separate line.

Ryan Merritt
Ryan Merritt
5,789 Points

The range function is a great way to loop for a specified number of times. For example:

range(5)

returns

[0, 1, 2, 3, 4]

So instead of

for num in 4:

try

for num in range(4):
Milagros Roman
Milagros Roman
1,228 Points

I tried different things but not successful I would like to have more help because this challenge was not explained and I got confused and I can't advance with other things. thank you

Milagros Roman
Milagros Roman
1,228 Points

Kenneth your course is really very nice but I cannot use the python workplace to exercise because I modify something and I receive error of connection I try again and again and each time error again sorry

Chelsea Anna
Chelsea Anna
417 Points

I am having this same issue, although despite this error, I am still receiving some feedback (such as an incorrect output). I'm not sure what's going on.

Milagros Roman
Milagros Roman
1,228 Points

thank you. I had finish last Friday in a similar ways as yours. thank you very much Chris Mila

Kenneth Love
STAFF
Kenneth Love
Treehouse Guest Teacher

You don't need range() for this code challenge at all.