r - 创建一个从开始计数到当前值的列表

Question

我目前有一个如下所示的数据表:

Name     Person     Date
A        1          1/1/2004
A        2          1/3/2004
A        3          1/9/2004 
B        4          1/7/2004
B        5          1/10/2004 
B        6          1/17/2004

我正在尝试创建一个如下所示的新数据表:

Name     Person     Date
A        1          1/1/2004
A        2          1/1/2004
A        2          1/3/2004
A        3          1/1/2004
A        3          1/3/2004
A        3          1/9/2004
B        4          1/7/2004
B        5          1/7/2004
B        5          1/10/2004
B        6          1/7/2004
B        6          1/10/2004
B        6          1/17/2004

日期从名称组的最小日期开始。

到目前为止，我做了这样的事情:

data$D = ave(data$Date, data$Name, FUN=min)
diff =  data$Date - data$D
sequence(diff) + rep(data$D,diff)

但是，这只会产生一个重复，该重复也会计算其间的日期。有没有一种简单的方法可以从最短日期开始扩展？谢谢!

Answer 1

您似乎正在寻找 data.table 解决方案，所以这里是

library(data.table)
setDT(data)[, list(Person = rep(Person, seq_len(.N)),
                   Date = Date[sequence(seq_len(.N))]), by = Name]

#     Name Person      Date
#  1:    A      1  1/1/2004
#  2:    A      2  1/1/2004
#  3:    A      2  1/3/2004
#  4:    A      3  1/1/2004
#  5:    A      3  1/3/2004
#  6:    A      3  1/9/2004
#  7:    B      4  1/7/2004
#  8:    B      5  1/7/2004
#  9:    B      5 1/10/2004
# 10:    B      6  1/7/2004
# 11:    B      6 1/10/2004
# 12:    B      6 1/17/2004

---

编辑

这是用于此答案的数据集

data <- structure(list(Name = structure(c(1L, 1L, 1L, 2L, 2L, 2L), .Label = c("A", 
        "B"), class = "factor"), Person = 1:6, Date = structure(c(1L, 
        4L, 6L, 5L, 2L, 3L), .Label = c("1/1/2004", "1/10/2004", "1/17/2004", 
        "1/3/2004", "1/7/2004", "1/9/2004"), class = "factor")), .Names = c("Name", 
         "Person", "Date"), class = "data.frame", row.names = c(NA, -6L
         ))