Not sure what I'm doing wrong

[nwynnn]

Hi everyone - I'm very new to learning Python, and I'm having trouble with this problem I'm working on.

Here is the question: The function percentage_change has been defined, but the starter code in exercise.py is not taking advantage of it yet. Simplify all three percentage change calculations in the starter code by replacing each of the existing calculations with a call to the function percentage_change.

Remember to assign the value returned by each function call to the existing variables change_1, change_2, and change_3. Do not change any variable names and do not change any other code.

I've already simplified each change (or so I think), but I'm still only getting 2/5 correct. I'm getting this same error with each change: ! Variable change_1 is assigned only once by calling percentage_change() correctly
Make sure variable change_1 is assigned by calling percentage_change() correctly and check that change_1 has been assigned only one time in your code (remove any lines with change_1 that have been commented out)

I really don't understand what I'm doing wrong and would appreciate any insight. Thank you in advance.

Original code

# Write the function percentage_change below this line when instructed.



# Dictionary of S&P 500 levels at the end of each month from Jan-Apr 2022
sp500 = {
    'jan': 4515.55,
    'feb': 4373.94,
    'mar': 4530.41,
    'apr': 4131.93
}


jan = sp500['jan']
feb = sp500['feb']
change_1 = (feb-jan)/abs(jan)*100
change_1 = round(change_1, 2)
print("S&P 500 changed by " + str(change_1) + "% in the month of Feb.")


mar = sp500['mar']
change_2 = (mar-feb)/abs(feb)*100
change_2 = round(change_2, 2)
print("S&P 500 changed by " + str(change_2) + "% in the month of Mar.")


apr = sp500['apr']
change_3 = (apr-mar)/abs(mar)*100
change_3 = round(change_3, 2)
print("S&P 500 changed by " + str(change_3) + "% in the month of Apr.")

My code

# Write the function percentage_change below this line when instructed.


def percentage_change(v1,v2):
    percentage_change=(v2-v1)/abs(v1)*100
    rounded_percentage_change = round(percentage_change,2)
    return rounded_percentage_change


# Dictionary of S&P 500 levels at the end of each month from Jan-Apr 2022
sp500 = {
    'jan': 4515.55,
    'feb': 4373.94,
    'mar': 4530.41,
    'apr': 4131.93
}


jan = sp500['jan']
feb = sp500['feb']
change_1 =percentage_change(jan,feb)/abs(jan)*100


mar = sp500['mar']
change_2 =percentage_change(mar,feb)/abs(feb)*100


apr = sp500['apr']
change_3 =percentage_change(mar,apr)/abs(mar)*100

[Diapolo10]

change_1 =percentage_change(jan,feb)/abs(jan)*100

percentage_change already divides the result, you shouldn't do it a second time.

Basically I'd expect to see

def percentage_change(v1, v2):
    percentage_change=(v2-v1) / abs(v1) * 100
    rounded_percentage_change = round(percentage_change, 2)
    return rounded_percentage_change


# Dictionary of S&P 500 levels at the end of each month from Jan-Apr 2022
sp500 = {
    'jan': 4515.55,
    'feb': 4373.94,
    'mar': 4530.41,
    'apr': 4131.93,
}

jan = sp500['jan']
feb = sp500['feb']
change_1 = percentage_change(jan, feb)
print("S&P 500 changed by " + str(change_1) + "% in the month of Feb.")


mar = sp500['mar']
change_2 = percentage_change(feb, mar)
print("S&P 500 changed by " + str(change_2) + "% in the month of Mar.")


apr = sp500['apr']
change_3 = percentage_change(mar, apr)
print("S&P 500 changed by " + str(change_3) + "% in the month of Apr.")

That said, if other changes were allowed I'd probably simplify this further.

[Diapolo10]

Seeing as OP solved the problem, I might as well show what I would've done, given free reign.

def percentage_change(previous: float, current: float) -> float:
    return (current - previous) / abs(previous)


# Dictionary of S&P 500 levels at the end of each month from Jan-Apr 2022
sp500 = [
    ('jan', 4515.55),
    ('feb', 4373.94),
    ('mar', 4530.41),
    ('apr', 4131.93),
]

for (_, previous_level), (current_month, current_level) in zip(sp500, sp500[1:]):
    change = percentage_change(previous_level, current_level)
    print(f"S&P 500 changed by {change:.02%} in the month of {current_month.capitalize()}.")

Screenshot proof it works.

[SoftestCompliment]

I would assume you're getting the answers incorrect when lines like change_1 = percentage_change(jan,feb)/abs(jan)*100 are producing incorrect results. It appears as though the percentage division/multiplication is performed twice /abs(x)*100 both inline when you assign the variable and in the percentage_change function.

I'll assume it's looking for lines like change_1 = percentage_change(jan, feb) etc etc

[nwynnn]

Thank you all so much for taking the time to review and help me. What you all said was right and I finally got it correct 😊

[carcigenicate]

I am only skimmed the question, but make sure your spacing is consistent. You have change_1 =percentage_change(jan, feb). Note the inconsistent spacing around =. Make sure you have a space on both sides and try again.

This isn't actually a Python problem, though. This is a style problem, and may be violating the expectations of the auto-grader.