Question

我正在完成关于CodeAcademy的Python课程（我在我的计算机上运行代码而不是CodeAcademy）并编写了这段代码来将项目添加到购物车。购物车是一本字典。

class ShoppingCart(object):

    """Creates shopping cart objects
    for users of our fine website."""

    items_in_cart = {}

    def __init__(self, customer_name):
        self.customer_name = customer_name

    def add_item(self, product, price):
        """Add product to the cart."""
        if not product in self.items_in_cart:
            self.items_in_cart[product] = price
            print product + " added."
        else:
            print product + " is already in the cart."

my_cart = ShoppingCart("Amy")

my_cart.add_item("Nishiki Modulus", "$400")

print my_cart.items_in_cart

此代码有效并返回：

Nishiki Modulus added.
{'Nishiki Modulus': '$400'}

但我想弄清楚如何同时添加几个项目（和价格）。我一直在试验没有运气。

我跑了

class ShoppingCart(object):

    items_in_cart = {}
    def __init__(self, customer_name):
        self.customer_name = customer_name

    def add_item(self, product, price):
        """Add product to the cart."""
        for products in product:
            if not products in self.items_in_cart:
                self.items_in_cart[products] = price
                print "added."
            else:
                print "Product is already in the cart."

my_cart = ShoppingCart("Amy")

my_cart.add_item(["Nishiki Modulus", "Trek 700", "Fuji Sportif"], ["$400", "$450", "$700"])

print my_cart.items_in_cart

正如我预测的那样，关键是正确的，但不是价值观。这将返回：

added.
added.
added.
{'Trek 700': ['$400', '$450', '$700'], 'Fuji Sportif': ['$400', '$450', '$700'],     'Nishiki Modulus': ['$400', '$450', '$700']}

我想的是：

for products, price in product.items():

但后来我无法弄清楚如何正确地将列表添加到items_in_cart

有人能指出我正确的方向吗？如果有任何不清楚的地方，请告诉我。

Answer 1

您可zip这些产品及其价格

for prod, money in zip(product, price):
    if not prod in self.items_in_cart:
        self.items_in_cart[prod] = money
        print "added."
    else:
        print "Product is already in the cart."

这将压缩product和price列表，并从两个列表中一次提供一个值。所以我们将得到产品及其相应的价格。

或者您可以迭代product列表，并使用索引从price获取相应的值，如下所示

for index, prod in enumerate(product):
    if not prod in self.items_in_cart:
        self.items_in_cart[prod] = price[index]
        print "added."
    else:
        print "Product is already in the cart."

Answer 2

您可以尝试使用简单索引for循环：

def add_item(self, product, price):
    """Add product to the cart."""
    for index in range(len(product):
        if not product[index] in self.items_in_cart:
            self.items_in_cart[product[index]] = price[index]
            print "added."
        else:
            print "Product is already in the cart."

或使用zip：

for products, prices in zip(product, price):

Answer 3

您正在将items_in_cart [product]的值设置为price，即字符串列表。您应该将其设置为价格中的一个字符串。

这是ShoppingCart类已修复：

class ShoppingCart(object):

    items_in_cart = {}
    def __init__(self, customer_name):
        self.customer_name = customer_name

    def add_item(self, product, price):
        """Add product to the cart."""
        priceIndex = 0
        for products in product:
            if not products in self.items_in_cart:
                self.items_in_cart[products] = price[priceIndex]
                print "added."

            else:
                print "Product is already in the cart."

            priceIndex += 1

Answer 4

我会添加一个新方法add_items，在循环中调用原始add_item。这将使您的代码更清晰，更易于使用。

class ShoppingCart(object):

    items_in_cart = {}
    def __init__(self, customer_name):
        self.customer_name = customer_name

    def add_item(self, product, price):
        """Add product to the cart."""
        if not product in self.items_in_cart:
            self.items_in_cart[product] = price
            print product + " added."
        else:
            print product + " is already in the cart."

    def add_items(self, products, prices):
        for product, price in zip(products, prices):
            self.add_item(product, price)

my_cart = ShoppingCart("Amy")

my_cart.add_items(["Nishiki Modulus", "Trek 700", "Fuji Sportif"], ["$400", "$450", "$700"])
print my_cart.items_in_cart

Python：将多个产品和价格添加到购物车

4 个答案: