擅长:python、mysql、java
<pre><code>df['decision']=df['CategoryB'].map(df.groupby('CategoryB')['Count'].\
apply(lambda x :np.where(x.sum()>0,'keep','delete')))
df
Out[573]:
CategoryA CategoryB Count decision
0 1 A 0 delete
1 1 A -1 delete
2 2 B 1 keep
3 2 B 1 keep
4 3 C 1 delete
5 3 C -1 delete
</code></pre>