擅长:python、mysql、java
<p>无需来回转换<code>timedelta</code>。Numpy和pandas可以以更快的运行时间无缝地为您完成这项任务。使用<code>dropped</code><code>DataFrame</code>:</p>
<pre class="lang-py prettyprint-override"><code>import numpy as np
grouped = dropped.groupby('bank')['diff']
mean = grouped.apply(lambda x: np.mean(x))
std = grouped.apply(lambda x: np.std(x))
</code></pre>