擅长:python、mysql、java
<p>我相信你需要<a href="https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.join.html" rel="nofollow noreferrer">pandas.join</a>。你知道吗</p>
<pre><code>res = df1.join(df2.set_index('DAY'), on='DAY')
</code></pre>
<p>并将size列/fill N/A重命名为0's</p>