Why is my dictionary not being changed outside of my function-CodePudding

Any changes that I make in products inside the function changeproducts is not being set outside of the function.

products = {
    "apple": {"price": 3.5, "stock": 134},
    "banana": {"price": 6.82, "stock": 52},
    "cake": {"price": 23, "stock": 5}
    }


def changeproducts():
    #operator enter new products
    items = input("Items: ").split()
    prices = map(float, input("Prices: ").split())
    stocks = map(int, input("Stocks: ").split())
    products = {
        item: {"price": price, "stock": stock} 
        for item, price, stock in zip(items, prices, stocks)
    }
    print (products)


changeproducts()
print(products)

CodePudding user response：

Python functions can't assign to variables in global scope by default, so it would be creating a new dictionary instead. Add global products to the top of the function:

def changeproducts():
  global products
  ...

CodePudding user response：

As Toggle said, edits within a function only exist to that function or it's sub-functions. You can either use a global variable as suggested,

def changeproducts():
    global products
    ...

But you can also use parameters return values instead

def changeproducts(func_products):
    #use `func_products` instead of `products`
    ... 
    return func_products

products = changeproducts(products)
print(products)

When changeproducts is called, you give it the value of products, which it saves as func_products. Then once the function code has finished, it gives func_products as it's return value. The return value is then saved into the products variable again

For more info, check the docs

CodePudding user response：

Instead of reassigning the value, you can simply modify the list by using its update method, so in changeproducts do:

products.update(
    {
        item: {"price": price, "stock": stock}
        for item, price, stock in zip(items, prices, stocks)
    }
)