擅长:python、mysql、java
<pre><code>mins = df.groupby("num")["dt"].min()
print(mins)
</code></pre>
<p>输出:</p>
<p><a href="https://i.stack.imgur.com/LdiUz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LdiUz.png" alt="enter image description here"/></a></p>