<p>另一种方法是使用<a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.groupby.html" rel="nofollow noreferrer">^{<cd1>}</a></p>
<pre><code>>>> departments = ['A', 'B', 'C', 'D']
>>> df.groupby('Name').apply(lambda _, L=departments: L).explode().to_frame('Department')
Department
Name
Ellen A
Ellen B
Ellen C
Ellen D
Joe A
Joe B
Joe C
Joe D
Zach A
Zach B
Zach C
Zach D
</code></pre>
<hr/>
<p>或者<a href="https://pandas.pydata.org/docs/reference/api/pandas.Series.reset_index.html" rel="nofollow noreferrer">^{<cd2>}</a>有一个<code>name</code>参数:在这种配置中很方便:</p>
<pre><code>>>> df.groupby('Name').apply(lambda _, L=departments: L).explode().reset_index(name='Department')
Name Department
0 Ellen A
1 Ellen B
2 Ellen C
3 Ellen D
4 Joe A
5 Joe B
6 Joe C
7 Joe D
8 Zach A
9 Zach B
10 Zach C
11 Zach D
</code></pre>