各位大大好,

假設dataframe 如下 :

index	name	amount
1	A	10
2	B	14
3	C	3
4	A	4
5	A	15
6	C	9
7	B	12
8	C	6
9	A	7

data <- data.frame(index = 1:9, name = c("A", "B", "C", "A", "A", "C", "B", "C", "A"), amount = c(10,14,3,4,15,9,12,6,7)

index	name	amount	times
1	A	10	1
4	A	4	2
5	A	15	3
9	A	7	4
2	B	14	1
7	B	12	2
3	C	3	1
6	C	9	2
8	C	6	3

請問如何做出 times 這种效果呢? 感謝