擅长:python、mysql、java
<p>您必须按年份和月份分组:</p>
<pre><code>import calendar # to use months' proper names
means = df.groupby([df.index.month, df.index.year]).mean()\
.unstack().reset_index(0, drop=True)\
.rename(dict(enumerate(calendar.month_abbr[1:])))
#ds 2017 2018
#ds
#Jan 3.5 5.0
#Feb 6.0 2.0
#Mar NaN 6.0
</code></pre>