b = { 'video':0, 'music':23,"picture":12 } 
random.choice(tuple(b.items())) ('music', 23) 
random.choice(tuple(b.items())) ('music', 23) 
random.choice(tuple(b.items())) ('picture', 12) 
random.choice(tuple(b.items())) ('video', 0) 

下面是一个字典类的Python代码，它可以在O(1)时间内返回随机键。(为了可读性，我在代码中包含了myypy类型):

from typing import TypeVar, Generic, Dict, List
import random

K = TypeVar('K')
V = TypeVar('V')
class IndexableDict(Generic[K, V]):
    def __init__(self) -> None:
        self.keys: List[K] = []
        self.vals: List[V] = []
        self.dict: Dict[K, int] = {}

    def __getitem__(self, key: K) -> V:
        return self.vals[self.dict[key]]

    def __setitem__(self, key: K, val: V) -> None:
        if key in self.dict:
            index = self.dict[key]
            self.vals[index] = val
        else:
            self.dict[key] = len(self.keys)
            self.keys.append(key)
            self.vals.append(val)

    def __contains__(self, key: K) -> bool:
        return key in self.dict

    def __len__(self) -> int:
        return len(self.keys)

    def random_key(self) -> K:
        return self.keys[random.randrange(len(self.keys))]

我需要遍历字典中的键的范围，而不是每次都对它排序，并找到了Sorted Containers库。我发现这个库可以通过索引随机访问字典项，直观地解决了这个问题，而不用每次都遍历整个字典:

>>> import sortedcontainers
>>> import random
>>> d = sortedcontainers.SortedDict({1: 'a', 2: 'b', 3: 'c'})
>>> random.choice(d.items())
(1, 'a')
>>> random.sample(d.keys(), k=2)
[1, 3]

从字典集dict_data中选择50个随机键值:

sample = random.sample(set(dict_data.keys()), 50)

一种方法是:

import random
d = {'VENEZUELA':'CARACAS', 'CANADA':'OTTAWA'}
random.choice(list(d.values()))

编辑:在最初的帖子发布几年后，这个问题被修改了，现在是一对，而不是一个。最后一行现在应该是:

country, capital = random.choice(list(d.items()))

b = { 'video':0, 'music':23,"picture":12 } 
random.choice(tuple(b.items())) ('music', 23) 
random.choice(tuple(b.items())) ('music', 23) 
random.choice(tuple(b.items())) ('picture', 12) 
random.choice(tuple(b.items())) ('video', 0)