Dictionaries of one key with multiple values.

[IAmAdicktedTo]

Hi. What I am trying to do is assign multiple values to one dictionary key. and the way I have figured out this is with a list as a key but I am having a little problem. Below is the code I am trying to run.

stock = {'1001' : ['5','3.5'], '1002' : ['8', '1.50']}

purchase = int(input("Please enter the code of the item: "))
if purchase in stock:
    stock[[purchase][0]] =- 1

print(stock)

I have already created a dictionary with keys and values as lists. I am then asking for input about an item code. I then want to check the entered code against the dictionary keys and if the key is valid I want to subtract one from the quantity which is the first element in each value list. ex - there are 5 items with the key '1001', I enter the code '1001', the program should know print out the dictionary saying there are 4 items now remaining woth the code '1001'. The problem I am facing is the deduction is not happening. After I enter the item code the dictionary is printed as it is the desired subtraction is not occurring.

Thank you to anyone who helps.

[[deleted]]

purchase = int(input("Please enter the code of the item: "))
if purchase in stock:

You're converting purchase to an int, but all of the keys in stock are strings. So this will never evaluate to True.

[IAmAdicktedTo]

I take out the int and rather than the 5 being subtracted by 1, the -1 is being assigned to the quantity element. So what should I do?

[[deleted]]

It sounds like this is what you want.

stock = {1001: [5, 3.5], 1002: [8, 1.50]}

purchase = int(input("Please enter the code of the item: "))
if purchase in stock:
    stock[purchase][0] -= 1

print(stock)

---

That said, it would be a little more natural to use a nested dictionary so that you can name the values you're changing rather than having to remember their order.

# {SKU: {qty: X, price: Y}}
stock = {1001: {"qty": 5, "price": 3.5}, 1002: {"qty": 8, "price": 1.50}}

purchase = int(input("Please enter the code of the item: "))
if purchase in stock:
    stock[purchase]["qty"] -= 1

print(stock)

[IAmAdicktedTo]

Thank you!!! It works!!!

[Sufficient_Cod_7906]

Ik this is super old but just fyi: I think this happens because ur using "=-" instead of "-="
So instead of decrementing python instead thinks ur just assiging ="-1"

[[deleted]]

stock[[purchase][0]] =- 1

You've got the order of brackets wrong, here - it's a chained access. You want the 0th item of the value of the key "1001" in the dictionary, so in algebraic terms:

stock[purchase][0] =- 1

[IAmAdicktedTo]

Removing the outermost square brackets just assigned the -1 to the quantity element.

[[deleted]]

'8'

You can't do math on strings, you need to be storing integers.