擅长:python、mysql、java
<p>如果您知道字典将只包含一个键值对,则可以使用赋值(注意<a href="https://docs.python.org/3/reference/simple_stmts.html#assignment-statements" rel="nofollow noreferrer">target list</a>中的逗号)来提取键或值:</p>
<pre><code>>>> d = {"Something": {"one": 1, "two": 2, "three": 3}}
>>> key, = d
>>> key
'Something'
>>> value, = d.values()
>>> value
{'one': 1, 'two': 2, 'three': 3}
</code></pre>
<p>如果键的数量不是一,则会抛出<code>ValueError</code>:</p>
<pre><code>>>> key, = {"foo": 1, "bar": 2}
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: too many values to unpack (expected 1)
</code></pre>