从另一个字典的值中减去值字典

Question

我需要从咖啡机所拥有的基本资源（水、咖啡、牛奶）中减去字典中给出的咖啡成分（用户选择 = 浓缩咖啡、拿铁、卡布奇诺）。这些资源在另一本词典中给出。在用户选择要喝的咖啡后，如何将它们相减？

MENU = {
    "espresso": {
        "ingredients": {
            "water": 50,
            "coffee": 18,
        },
        "cost": 1.5,
    },
    "latte": {
        "ingredients": {
            "water": 200,
            "milk": 150,
            "coffee": 24,
        },
        "cost": 2.5,
    },
    "cappuccino": {
        "ingredients": {
            "water": 250,
            "milk": 100,
            "coffee": 24,
        },
        "cost": 3.0,
    }
}

resources = {
    "water": 300,
    "milk": 200,
    "coffee": 100,
}

从之前的课程中，我了解到我需要格式化字典中的数据，以便它可以在代码中使用。但我处于非常初级的水平，格式化数据后我陷入困境。

def format_data(choice):
    """Format ingredients into printable format: water, milk, coffee, cost"""
    water = MENU[user_choice]['ingredients']["water"]
    milk = MENU[user_choice]['ingredients']["milk"]
    coffee = MENU[user_choice]['ingredients']["coffee"]
    cost = MENU[user_choice]['ingredients']["cost"]

user_choice = input("What would you like? (espresso/latte/cappuccino").lower()

Answer 1

这里有一个方法：

• 询问用户想要的饮料

• 使用他们选择的饮料和 Python

  in

   运算符检查该饮料是否在 

  MENU

   字典中

• 如果饮料

  在MENU字典中，则使用饮料选择作为

  MENU

  的键来查找配方（成分和数量） 他们的饮料（

  例如。

  MENU[choice]['ingredients']）

检查配方中的每种成分和数量，并从
• resources

  字典中的相同成分中减去该数量

    MENU = {
        "espresso": {
            "ingredients": {
                "water": 50,
                "coffee": 18,
            },
            "cost": 1.5,
        },
        "latte": {
            "ingredients": {
                "water": 200,
                "milk": 150,
                "coffee": 24,
            },
            "cost": 2.5,
        },
        "cappuccino": {
            "ingredients": {
                "water": 250,
                "milk": 100,
                "coffee": 24,
            },
            "cost": 3.0,
        }
    }
  
    resources = {
        "water":  3000,
        "milk":   2000,
        "coffee": 1000,
    }
  
    # go into a 'forever' loop and prompt the user for their drink choice
  
    while True:
        choice = input("choice: ")
  
        # if input line has a 'q' in it then quit (break out of loop)
        if 'q' in choice:
            print("all done")
            break
  
        # if input line is not a known drink then prompt to try again
        if choice not in MENU:
            print("don't have that on the menu try again")
            continue
  
        # if we get here we know its a known drink so get the recipe
        # for the chosen drink and assign it to the the recipe dictionary
        recipe = MENU[choice]['ingredients']
  
        # now go through the recipe for the chosen drink and 
        # for each ingredient subtract the quantity of that
        # ingredient used from the resources dictionary
  
        for ingredient, quantity in recipe.items():
            resources[ingredient] -= quantity
  
        # report the drink was made
        print ("made you a", choice)
  
        # report the remaining resources after the drink was made
        print ("remaining resources are:")
        for ingredient, quantity in resources.items():
            print(f"{ingredient:6} {quantity:6}")