擅长:python、mysql、java
<p>有一个办法</p>
<pre><code>In [386]: L = [['34', '345'], ['12', '23,534,34'], ['1', '13,42']]
In [387]: (pd.DataFrame(L, columns=['UserID', 'ListID'])
.set_index('UserID')
.ListID.str.split(',')
.apply(pd.Series)
.stack()
.reset_index(level=0, name='ListID'))
Out[387]:
UserID ListID
0 34 345
1 12 23
2 12 534
3 12 34
4 1 13
5 1 42
</code></pre>