r - 变量创建 - 推断年龄

Question

我有一个分组数据框；

Truck <- c('A','A','A','A','B','B','B','B','C','C','C','C')
OilChanged <- c('True','NewOil','False','False','False','False','False','False','True','NewOil','True','NewOil')
Odometer <- c(1000, 1000, 2000,3000,700,800,900,1000,20000,20000,30000,30000)
DF <- data.frame(Truck, OilChanged, Odometer)

# Truck OilChanged Odometer
# 1      A       True     1000
# 2      A     NewOil     1000
# 3      A      False     2000
# 4      A      False     3000
# 5      B      False      700
# 6      B      False      800
# 7      B      False      900
# 8      B      False     1000
# 9      C       True    20000
# 10     C     NewOil    20000
# 11     C       True    30000
# 12     C     NewOil    30000

我试图在可能的情况下推断油的年龄(以公里为单位)。只有在发生换油后才能进行推断。如果不更换机油，机油的年龄将仍然是个谜(例如:卡车 B)。
下面是想要的结果；

Truck <- c('A','A','A','A','B','B','B','B','C','C','C','C')
OilChanged <- c('True','NewOil','False','False','False','False','False','False','True','NewOil','True','NewOil')
Odometer <- c(1000, 1000, 2000, 3000,700,800,900,1000,20000,20000,30000,30000)
OilAge <- c(NA,0,1000,2000,NA,NA,NA,NA,NA,0,10000,0)
Result <- data.frame(Truck, OilChanged, Odometer, OilAge)


# Truck OilChanged Odometer OilAge
# 1      A       True     1000     NA
# 2      A     NewOil     1000      0
# 3      A      False     2000   1000
# 4      A      False     3000   2000
# 5      B      False      700     NA
# 6      B      False      800     NA
# 7      B      False      900     NA
# 8      B      False     1000     NA
# 9      C       True    20000     NA
# 10     C     NewOil    20000      0
# 11     C       True    30000  10000
# 12     C     NewOil    30000      0

注意:里程表读数介于 之间真换油行，它跟随 新油行将始终相同。因为油样是在换油前直接采集的。但必须维护两行，以便下游计算正常运行，例如变化率公式。
OilAge 列中的 NA 表示年龄是个谜。

Answer 1

请让我知道此解决方案是否适合您。

Truck <- c('A','A','A','A','B','B','B','B','C','C','C','C')
OilChanged <- c('True','NewOil','False','False','False','False','False','False','True','NewOil','True','NewOil')
Odometer <- c(1000, 1000, 2000,3000,700,800,900,1000,20000,20000,30000,30000)
DF <- data.frame(Truck, OilChanged, Odometer)

DF %>%
  group_by(Truck) %>%
  mutate(status = length(unique(OilChanged)),
         OilAge = ifelse(OilChanged == "NewOil", 0,
                         ifelse(OilChanged == "False", Odometer - (Odometer - lag(Odometer)),
                                ifelse(OilChanged == "True", Odometer - lag(Odometer), NA)))) %>%
  mutate(OilAge = ifelse(status !=1, OilAge, NA)) %>%
  subset(select = c(Truck, OilChanged, Odometer, OilAge))