擅长:python、mysql、java
<p>您需要将参数<code>group_keys=False</code>添加到<a href="http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.groupby.html" rel="nofollow noreferrer">^{<cd2>}</a>:</p>
<pre><code>a = df.groupby(level=0, group_keys=False).apply(lambda x: x.sort_values('C1'))
print (a)
C1 C2
A 4 -0.103219 0.410599
3 0.950088 -0.151357
1 0.978738 2.240893
0 1.764052 0.400157
2 1.867558 -0.977278
C 0 0.144044 1.454274
4 0.313068 -0.854096
2 0.443863 0.333674
1 0.761038 0.121675
3 1.494079 -0.205158
</code></pre>