擅长:python、mysql、java
<p>流行的<code>pandas</code>库允许您在一行中执行此操作:</p>
<pre><code>import pandas as pd
complete_items_per_user = pd.DataFrame(data).groupby('userId')['completed'].sum()
</code></pre>
<p>如果你在问没有<code>pandas</code>你能做些什么,你可以通过听写理解来避免显式循环:</p>
<pre><code>users = set(x['userId'] for x in data)
complete_items_per_user = {user: sum(x['completed'] for x in data if x['userId']==user) for user in users}
</code></pre>