python之如何通过 Python 中单个字典的键对一堆列表进行分组

我有一堆列表，其中包含彼此相关的元素，我想将它们转换为一个以列表作为值的字典:

list1 = ['cat', 'animal'] 
list2 = ['dog', 'animal'] 
list3 = ['crow', 'bird'] 
 
result = {'animal': ['cat', 'dog'], 'bird': 'crow'} 

我该怎么做？

请您参考如下方法:

简单方法:

data = [['cat', 'animal'], ['dog', 'animal'], ['crow', 'bird']] 
 
result = {} 
 
for value, key in data: 
    result[key] = result.get(key, []) + [value] 
 
result #=> {'bird': ['crow'], 'animal': ['cat', 'dog']} 

使用defaultdict:

from collections import defaultdict 
 
data = [['cat', 'animal'], ['dog', 'animal'], ['crow', 'bird']] 
 
result = defaultdict(list) 
 
for value, key in data: 
    result[key].append(value) 
 
result #=> defaultdict(<class 'list'>, {'animal': ['cat', 'dog'], 'bird': ['crow']}) 

使用 itertools 中的 groupby:

from itertools import groupby 
 
data = [['cat', 'animal'], ['dog', 'animal'], ['crow', 'bird']] 
 
{k: [x[0] for x in g] for k, g in groupby(data, lambda x: x[1])} 
#=> {'bird': ['crow'], 'animal': ['cat', 'dog']} 

使用 functools 中的 reduce:

from functools import reduce 
 
data = [['cat', 'animal'], ['dog', 'animal'], ['crow', 'bird']] 
 
reduce(lambda a, e: dict(a, **{e[1]: a.get(e[1], []) + [e[0]]}), data, {}) 
#=> {'bird': ['crow'], 'animal': ['cat', 'dog']}