当时间序列数据偏移且不完整时

工作中的新客户有一个从3月开始到次年2月结束的会计日历:

fiscalMonthLabels <- c("March", "April", "May", "June", 
  "July", "August", "September", "October", 
  "November", "December", "January", "February")

但是,因为它们是新的,我们只有几个月的数据:

library(lubridate)
rawDate <- c("2018-09-01", "2018-10-01", "2018-11-01")
actualMonth <- month(rawDate)
newMonth <- rep(0, length(actualMonth))
for (i in 1:length(actualMonth)) {
  if (actualMonth[i] == 1) {newMonth[i] <- 11} 
  else if (actualMonth[i] == 2) {newMonth[i] <- 12} 
  else {newMonth[i] <- actualMonth[i] - 2}
}
revenue <- c(123, 456, 789)

df <- data.frame(rawDate, actualMonth, newMonth, revenue)
df
     rawDate actualMonth newMonth revenue
1 2018-09-01           9        7     123
2 2018-10-01          10        8     456
3 2018-11-01          11        9     789

因此,当我尝试用会计月创建一个新因子时,我得到的错误是:

fiscalMonth <- factor(newMonth, labels = fiscalMonthLabels)

Error in factor(newMonth, labels = fiscalMonthLabels) : 
    invalid 'labels'; length 12 should be 1 or 3

好像 factor 司令部正在寻找 actualMonth