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))

ydata :

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

如何能在 ydata, 做出以下效果呢, 不停的1,0,1,0到dataframe 的尾

index	name	amount	type
1	A	10	1
2	B	14	0
3	C	3	1
4	A	4	0
5	A	15	1
6	C	9	0
7	B	12	1
8	C	6	0
9	A	7	1