Pandas DataFrame计算重复行并填充列

Question

我创建了一个DataFrame，现在需要计算每个重复行（例如df [＆＃39; Gender＆＃39;]。假设性别＆＃39;男性出现两次，女性出现三次，我需要这个专栏：

Gender   Occurrence
Male     1
Male     2
Female   1
Female   2
Female   3

Pandas有办法做到这一点吗？

Answer 1

按Gender

分组后使用cumcount方法

df = pd.DataFrame({'Gender':['Male','Male','Female','Female','Female']})   
df['Occurrence'] = df.groupby('Gender').cumcount() + 1
print(df)

   Gender  Occurrence
0    Male           1
1    Male           2
2  Female           1
3  Female           2
4  Female           3

计数从0开始，所以我在那里添加了+ 1。