变换计数连续整数

Question

我有一个像

这样的数据集

id
1
2
3
4
7
8

我希望输出为：

id   count
1     4
2     4
3     4
4     4
7     2
8     2

提前致谢

Answer 1

通过 Series.diff, compare for not equal 1 by Series.ne and add cumulative sum by Series.cumsum:

为连续整数创建 Series

s = df['id'].diff().ne(1).cumsum()

然后使用Series.map with Series.value_counts:

df['count'] = s.map(s.value_counts())

或GroupBy.transform with GroupBy.size:

df['count'] = s.groupby(s).transform('size') 

print (df)
   id  count
0   1      4
1   2      4
2   3      4
3   4      4
4   7      2
5   8      2