Python 2.7：将具有重复值的2个列表放入字典中

Question

如果我有2个列表：fruits = ["apple","apple","oranges","watermelon","apple"]val = ["a","b","c","d","e"]val的每个索引对应于水果的索引因此，如果我想要具有以下内容的字典：dict{"apple" : ["a","b","e"],"oranges": ["c"],"watermelon": ["d"]}最简单的方法是什么？

Answer 1

使用defaultdictwithlist工厂作为输出容器，并使用以下命令遍历两个列表zip：

In [162]: out = collections.defaultdict(list)

In [163]: for k, v in zip(fruits, val):

     ...:     out[k].append(v)

     ...:     

In [164]: out

Out[164]: 

defaultdict(list,

            {'apple': ['a', 'b', 'e'], 'oranges': ['c'], 'watermelon': ['d']})

In [165]: dict(out)

Out[165]: {'apple': ['a', 'b', 'e'], 'oranges': ['c'], 'watermelon': ['d']}

Answer 2

您可以使用setdefault一个空列表初始化每个值，然后附加另一个列表中的值

fruits = ["apple","apple","oranges","watermelon","apple"]

val = ["a","b","c","d","e"]

d={}

for k, v in zip(fruits, val):

    d.setdefault(k, []).append(v) 

print(d)

# {'apple': ['a', 'b', 'e'], 'oranges': ['c'], 'watermelon': ['d']}