假设我有：
A <- c(1,0,0,0)
B <- c(0,1,0,0)
C <- c(0,0,1,0)
D <- c(0,0,0,1)
data <- xts(cbind(A,B,C,D),order.by = as.Date(1:4))
然后我得到...
A B C D
1970-01-02 1 0 0 0
1970-01-03 0 1 0 0
1970-01-04 0 0 1 0
1970-01-05 0 0 0 1
我想为值为1的每一列提取日期。所以我想看看这样的东西...
A "1970-01-02"
B "1970-01-03"
C "1970-01-04"
D "1970-01-05"