Question

我正在使用python建立基本商店，其中包含商品及其价格的字典。我正在为购物车使用字典，希望用户能够向购物车中添加项目。为此，我旨在将键和值从产品字典复制到购物车字典。我该怎么办？

products = {"Pencil": 1, "Notebook": 2, "Backpack": 3, "Pens": 2, "Markers": 5, "Whiteboard": 30}
cart = {}

def addToCart():
    productToAdd = input("What would you like to add? ")
    for k,v in products.items():
        if productToAdd == k:
            price = v
            cart[productToAdd] = cart[v]
            break

Answer 1

products = {"Pencil": 1, "Notebook": 2, "Backpack": 3, "Pens": 2, "Markers": 5, "Whiteboard": 30}
cart = {}

def addToCart():
    try:
        productToAdd = input("What would you like to add? ")
        cart[productToAdd]=products[productToAdd]
    except KeyError:
        print("No such product")

请注意，python区分大小写，“ pencil”和“ Pencil”不同。如果您确定产品首先要成为大写字母，则可以使用

productToAdd = input("What would you like to add? ").title()

Answer 2

您可以使用dict.setdefault(key, default=None)
示例：

def addToCart():
    productToAdd = input("What would you like to add? ")
    cart[productToAdd]=products.setdefault(productToAdd, 'No such product')

Answer 3

假设用户将从列表中选择项目（尤其是从键中选择），则：

products = {"Pencil": 1, "Notebook": 2, "Backpack": 3, "Pens": 2, "Markers": 5, 
"Whiteboard": 30}

cart = {}


def addToCart():
    productToAdd = input("What would you like to add? ")
    if not productToAdd.title() in products: # for removing caps confusion
        print('No such item')
    else: cart[productToAdd] = products[productToAdd]


>>> addToCart()
What would you like to add? Pencil
>>> cart
{'Pencil': 1}

Answer 4

我不得不使用raw_input，否则它将无法接受“ Pencil”之类的字符串。这就是复制键值对的方式。

products = {"Pencil": 1, "Notebook": 2, "Backpack": 3, "Pens": 2, "Markers": 5, "Whiteboard": 30}

cart = {}

def addToCart():
    productToAdd = raw_input("What would you like to add? ")
    for k,v in products.items():
        print(k)
        if productToAdd == k:
            cart[k] = v
            break

addToCart()
print(cart)

将单个键值对从一个字典移动到另一个

4 个答案: