Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Python Python Basics Functions and Looping Raise an Exception

Kieran Forbes
Kieran Forbes
3,706 Points

Need help with my Python Code

I have written the code already but are finding problems with the Value Error and the bubble sort.

suggestinator.py
total = []
prices = []
print("Hi there, and welcome to our store, please enter 5 items you bought today along with their prices")

for loop in range(5):
        try:
                purchase = input("What did you buy today?")
                total.append(purchase)
                price = float(input("How much did it cost?"))
                prices.append(price)
        except ValueError:
                print("Please enter a valid number")


def bubbleSort(nlist):
    sorted = False
    while not sorted:
        swaps = 0
        for i in range(len(nlist) -1):
            if nlist[i] > nlist[i+1]:
                temp1 = nlist[i]
                nlist[i] = nlist[i + 1]
                nlist[i + 1] = temp1
                swaps = swaps + 1
        if swaps == 0:
             sorted = True
    return nlist

bubbling = (bubbleSort(prices))

first_total = (total[0], prices[0])
second_total = (total[1], prices[1])
third_total = (total[2], prices[2])
fourth_total = (total[3], prices[3])
fifth_total = (total[4], prices[4])

final_total = first_total, second_total, third_total, fourth_total, fifth_total
print(final_total)

discount = first_total
print("Since you bought 5 products with us today, we will now give you the cheapest product for free, meaning you will get", discount, "for free")


totaltotal =(prices[1], prices[2], prices[3], prices[4])
totaltotalt = sum(totaltotal)
print("So the total price that you will pay today is ",totaltotalt)
Chris Freeman
Chris Freeman
Treehouse Moderator 68,457 Points

Can describe the specific problem you are seeing?

Kieran Forbes
Kieran Forbes
3,706 Points

Thanks for your reply. The code is working fine and the loop produces the correct values after, but when testing the value error for example by keying in a word instead of a float, the code will run, until the last enret and then an index error would appear. So my ValueError is not working properly.

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,457 Points

This issue can be looked at in one of two ways:

  • try/except/ValueError does not guarantee that 5 prices and totals are captured, or
  • there are hardcoded expectations that 5 valid values are being returned

You may wish to change the for loop to while len(prices) < 5:

The hardcoded statements could be make to work with whatever values are present:

first_total = (total[0], prices[0])
final_total = list(zip(total, prices))
print(final_total)
discount = first_total
print("Since you bought", len(total), "products with us today, we will now give you the cheapest product for free, meaning you will get", discount, "for free")
totaltotal = prices[1:]
totaltotalt = sum(totaltotal)

Other issues:

  • Since bubbleSort operates on a mutable list, the argument will be modified in place. The return value bubbling is not necessary and isn't actually used. The sort can simply be called using bubbleSort(prices)
  • If a valid item is entered into total.append but prices fails due to ValueError then the length of total and prices will be different. Move the assignment of total.append to after the float(input(...)) then if the float fails, neither list is appended.
  • consider using Decimal class for money, since 0.1 + 0.1 + 0.1 = 0.30000000000000004 due to floating point roundoff errors

Post back if you have more questions. Good luck!!

Kieran Forbes
Kieran Forbes
3,706 Points

Thanks for your help, I appreciate it. lll try implement into my program what you mentioned.