<p>您可以使用<code>dict.get()</code>来获取特定键的值</p>
<pre><code>for d in voting_data:
county = d.get('county')
voters = '{:,}'.format(d.get('registered_voters'))
print(f'{county} county has {voters} registered voters.')
</code></pre>
<pre><code>Arapahoe county has 422,829 registered voters.
Denver county has 463,353 registered voters.
Jefferson county has 432,438 registered voters.
</code></pre>
<blockquote>
<p><strong>NOTE:</strong> <code>'{:,}'.format(100000)</code> results in formatting the number as <code>100,000</code> and returns a string which can be printed in the format you are looking for.</p>
</blockquote>
<hr/>
<p>理解嵌套数据结构的行为非常重要。可以使用<code>for-loop</code>在对象列表上迭代</p>
<pre><code>for item in list:
print(item)
</code></pre>
<p>在本例中,项目是字典。为了访问字典(键、值对),您可以直接从相应的键访问值</p>
<pre><code>d = {'k1':'v1',
'k2':'v2'}
>>> d['k1']
v1
#OR
>>> d.get('k1')
v1
</code></pre>
<p>如果您想迭代字典(键和值对),<strong>则需要额外的for循环</p>
<pre><code>for k,v in d.items():
print(k, v)
</code></pre>
<pre><code>(k1,v1)
(k2,v2)
</code></pre>
<p>希望这能澄清为什么在您的案例中不需要嵌套循环。因为您有一个字典列表,所以可以遍历该列表,然后使用每个字典的特定键访问每个字典(在本例中是county和registered_选民)</p>