计算列的连续出现次数

Question

我正在尝试计算 Products 列的连续出现次数。结果应如“总计数”列中所示。我尝试将 groupby 与 cumsum 一起使用，但我的逻辑无法正常工作

+----------+--------------+
| Products | Total counts |
+----------+--------------+
| 1        | 3            |
+----------+--------------+
| 1        | 3            |
+----------+--------------+
| 1        | 3            |
+----------+--------------+
| 2        | 1            |
+----------+--------------+
| 3        | 3            |
+----------+--------------+
| 3        | 3            |
+----------+--------------+
| 3        | 3            |
+----------+--------------+
| 4        | 2            |
+----------+--------------+
| 4        | 2            |
+----------+--------------+

Answer 1

使用 groupby 和 transform 并计数，

df['Total counts'] = df.groupby('Products').transform('count')

输出：

   Products  Total counts
0         1             3
1         1             3
2         1             3
3         2             1
4         3             3
5         3             3
6         3             3
7         4             2
8         4             2

---

连续产品，稍后在数据框中重复：

grp = (df['Products'] != df['Products'].shift()).cumsum()
df['Total counts'] = df.groupby(grp)['Products'].transform('count')

输出：

   Products  Total counts
0         1             3
1         1             3
2         1             3
3         2             1
4         3             3
5         3             3
6         3             3
7         4             2
8         4             2