擅长:python、mysql、java
<p>正如您在评论中所阐明的,您需要在当前<code>duplicated</code>旁边添加一个掩码</p>
<pre><code>m1 = df_so.duplicated(subset=['letter'], keep=False)
m2 = ~df_so.groupby('ID').letter.apply(lambda x: x.duplicated())
df_so['dup'] = m1 & m2
Out[157]:
ID letter dup
0 100 A True
1 100 B False
2 100 A False
3 200 C False
4 200 D True
5 300 E False
6 300 D True
7 300 A True
8 300 A False
</code></pre>
<p><strong>注意</strong>:我在评论中添加了<code>row=8</code></p>