如果不满足条件，请在data.frame中引用上面的行

使用data.frame

颜色

：

colors <- data.frame(color=c("Red","Light Red","Dark Red","Blue","Turquise", "Dark Blue","Cyan"),
                     level=c("Primary",rep("Secondary",2),"Primary",rep("Secondary",3)),
                     stringsAsFactors = F)

所需输出应为：

colorsOutput <- data.frame(color=c("Red","Light Red","Dark Red","Blue","Turquise", "Dark Blue","Cyan"),
                           level=c("Primary",rep("Secondary",2),"Primary",rep("Secondary",3)),
                           primary.color=c("Red","Red","Red","Blue","Blue", "Blue", "Blue"),
                           stringsAsFactors = F)

---

colorsOutput考虑到您的
数据。帧
已排序（先是原色，然后是次色），您可以执行以下操作：

colors$primary.color <- colors$color[colors$level=="Primary"][cumsum(colors$level=="Primary")]
colors
#      color     level primary.color
#1       Red   Primary           Red
#2 Light Red Secondary           Red
#3  Dark Red Secondary           Red
#4      Blue   Primary          Blue
#5  Turquise Secondary          Blue
#6 Dark Blue Secondary          Blue
#7      Cyan Secondary          Blue

colors$primary.color这是“最后一次观察结转”的一个很好的用例，即
zoo
软件包中的
na.locf
功能

首先获取原色所在位置的索引：

idx <- colors$level == "Primary"

idx
idx <- colors$level == "Primary"

colors[idx, "primary"] <- colors$color[idx]

colors$primary <- zoo::na.locf(colors$primary)