python - 如何仅向 python 询问新 key :value pairs?

Question

我正在寻找的内容很难解释，因此我向您展示我已有的代码和我正在寻找的输出。我尝试了在 stackoverflow 中找到的各种方法，但据我判断，没有一个解决方案适用于我的情况。

allGuests = {"Alice": {"apples": 5, "pretzels": 12}, "Bob": {"ham 
             sandwiches": 3, "apples": 2}, "Carol": {"cups": 3, "apple pies": 3}}
def totalBrought(guests, item): 
    numBrought = 0              
    for k, v in guests.items():                             
        numBrought = numBrought + v.get(item, 0) 
    return numBrought
while True:
    print("Is there another Guest coming?")
    answer = input()  
    if (answer == "Yes") or (answer == "yes"):
        newdishesDic = {}
        print("Who is it? ")
        newguest = input() 
        while True:
            print("What does " + newguest + " bring to the picnic?")
            newdish = input()
            print("How much of it?")
            newquantity = input()
            newdishesDic[newdish] = int(newquantity)
            allGuests[newguest] = newdishesDic
            print("Anything else?")
            answer2 = input()
            if (answer2 == "") or (answer2 == "no") or (answer2 == "No"):
                break
            elif (answer2 == "Yes") or (answer2 == "yes"):
                continue
    elif (answer == "") or (answer == "no") or (answer == "No"):
        break
print(" - Apples: " + str(totalBrought(allGuests, "apples")))
print(" - Pretzels: " + str(totalBrought(allGuests, "pretzels")))
....

等等。结果如下:

- Apples: 7
- Pretzels: 12
- Cups: 3
...

如您所见，我添加了新的客人、菜肴和数量，并将这些添加到现有的 allGuests 字典中。 但是，在事先不知道新菜肴的情况下，我如何才能对结果中所示的内容进行完全相同的“计数”呢？ 我尝试了各种方法，但在“最好的情况”下，我得到了最后添加的键值对，因为每次迭代都会覆盖变量(这有意义吗？)

我读到了关于字典理解作为解决方案的内容，但坦率地说，我并不太明白如何在这里使用它。我尝试不仅将新输入添加到字典中，还尝试将新输入添加到新列表中，但随后将不再有任何键值对，因此无法解决问题。 谁能遵循我模糊且最可能令人困惑的请求？

Answer 1

您想要生成一个新字典，在其中总结所有客人的所有菜肴。

from collections import defaultdict

def sum_up_all_dishes(all_guests):
    dishes = defaultdict(int)
    for dish in all_guests.values():
        for name, amount in dish:
            dishes[name] += amount
    return dishes

all_guests = {
    "Alice": {"apples": 5, "pretzels": 12}, 
    "Bob": {"ham sandwiches": 3, "apples": 2},
    "Carol": {"cups": 3, "apple pies": 3}
}

while True:
    print("Is there another Guest coming?")
    answer = input()  
    if answer.lower() == "yes":
        newdishesDic = {}
        print("Who is it? ")
        newguest = input() 
        while True:
            print("What does {} bring to the picnic?".format(newguest))
            newdish = input()
            print("How much of it?")
            newquantity = input()
            newdishesDic[newdish] = int(newquantity)
            print("Anything else?")
            answer2 = input()
            if answer2.lower() in ("", "no"):
                break
        all_guests[newguest] = newdishesDic
    else:
        break
all_dishes = sum_up_all_dishes(all_guests)
for name, amount in dishes.items():
    print(" - {}: {}".format(name, amount))