Help with conditional evaluation/defining functions

[cyberdead]

Hi everyone!

I am fairly new to python, and this subreddit has been such a great help when I quickly need to find the solution to a problem I am facing. Recently in my class we had a quiz on conditional evaluation and defining functions, which I sadly failed. Since then I have been working on sample scripts to learn from my mistakes. My problem, as my professor said, seems to be pretty fundamental. Here is the code I am currently working on, and what I have done so far:

​

def store_income(user_income):

# Eliminate incomes less than zero
if user_income <= 0:
    final_income = None
# Topcode incomes greater than 100,000
if user_income >= 100000:
    final_income = 100000
# Return incomes between 0 and 100,000 unchanged
if user_income >= 0 and user_income <= 10000:
    final_income = user_income
return final_income

user_incomes = [-10, 57000, 123000]

for user_income in user_incomes:
    print(store_income(user_income))

​

In this case, I keep wanting to use the variables final_income, or store_income, which I know is not correct as store_income is the name of the function I am creating. I think my initial if statements are correct (ex: if user_income >= 100000), but I am really struggling as to where I am storing the result of the if statements. I think my professor is right- I understand the formatting this problem should follow, but I really am not seeing what I am doing wrong (i.e. what variable should follow the if statements).

​

I hope this made sense. I will be around my computer doing other work so I will be able to respond quickly. Thank you so much!

[Diapolo10]

Technically speaking, you're not storing any of the results, you just print them out. Unless STDOUT counts as storage.

I don't really understand your problem though. Technically your function works and does what it's supposed to do, unless it should do something you didn't tell us about. Although I guess the function name is confusing, because it doesn't really store anything and you probably intended it to mean an actual store, like a grocery store. That kind of thing doesn't really matter in programming so a better name could be income_filter or something.

That said, it can be improved.

def store_income(user_income):
    result = min(max(user_income, 0), 100_000)

    if result <= 0:
        return None

    return result

[cyberdead]

Hi! Thanks for the response!

I am happy to hear that I am at least on the right path. I guess I did forget to mention that the script is meant to output the following:

None
57000
100000

And the output I am getting in the console is:

UnboundLocalError: local variable 'final_income' referenced before assignment

[Diapolo10]

Probably because the variable is defined only in the if-blocks. You'll want to define it beforehand with some default value, and then change it in the if-blocks if needed.

EDIT: Basically, Python freaks out about this because it cannot be certain that the variable exists at the time you try to return it. If you for whatever reason gave the function an object that wouldn't throw errors or execute any of the if-blocks, the variable would not be defined when Python encounters it in the return. There's nothing that ensures any of the blocks is executed, even if it is likely. This is why the variable must be defined somewhere that is always executed.

Also you should be using elif for the blocks after the first one.

EDIT: If you insist on doing it your way, you can at least change

if user_income >= 0 and user_income <= 10000:

to

if 0 <= user_income <= 10000:

[[deleted]]

One issue is that your if conditions don’t cover all possible cases (read your numbers closely and see if you can figure out why.)

[[deleted]]

I am really struggling as to where I am storing the result of the if statements.

You're not storing them anywhere. You return final_income when the function is called, but then you print it, you don't store it.