擅长:python、mysql、java
<p>您可以使用<code>groupby()</code>+<code>transform()</code>+<a href="https://pandas.pydata.org/pandas-docs/stable/generated/pandas.factorize.html" rel="nofollow noreferrer">^{<cd3>}</a>:</p>
<pre><code>In [12]: df['CumUniqueIDs'] = df.groupby('ID1')['ID2'].transform(lambda x: pd.factorize(x)[0]+1)
In [13]: df
Out[13]:
ID1 ID2 CumUniqueIDs
0 A X 1
1 A X 1
2 A Y 2
3 A Y 2
4 A Z 3
5 B L 1
6 B L 1
</code></pre>