python - 创建每个键有多个值的字典

Question

如何从 2 个列表中为每个键创建一个具有多个值的字典？

例如，我有:

>>> list1 = ['fruit', 'fruit', 'vegetable']

>>> list2 = ['apple', 'banana', 'carrot']

而且，我想要一些效果:

>>> dictionary = {'fruit': ['apple', 'banana'], 'vegetable': ['carrot']}

到目前为止，我已经尝试了以下方法:

>>> keys = list1
>>> values = list2
>>> dictionary = dict(zip(keys, values))
>>> dictionary
    {'fruit': 'banana', 'vegetable': 'carrot'}

Answer 1

您可以使用 dict.setdefault 和一个简单的 for 循环:

>>> list1 = ["fruit", "fruit", "vegetable"]
>>> list2 = ["apple", "banana", "carrot"]
>>> dct = {}
>>> for i, j in zip(list1, list2):
...     dct.setdefault(i, []).append(j)
... 
>>> dct
{'fruit': ['apple', 'banana'], 'vegetable': ['carrot']}

来自docs :

setdefault(key[, default])

If key is in the dictionary, return its value. If not, insert key with a value of default and return default. default defaults to None.