擅长:python、mysql、java
<p>这就是<a href="https://docs.python.org/2/library/collections.html#collections.Counter" rel="nofollow noreferrer">^{<cd1>}</a>的工作:</p>
<pre><code>from collections import Counter
counter = Counter(item['userId'] for item in items)
print(counter)
</code></pre>