如何在R中扩展日历周期以补全dataframe？

现有数据框testDF，其中ID为1的条目包含5个周期（Period_1代表月份数），ID为50和60的条目各有3个周期。已通过tidyr包完成Period_1的补全，让所有ID都拥有5个Period_1，同时向下填充了Bal和State字段。现在需要以相同逻辑扩展表示日历月份的Period_2，同时要处理跨年度滚动的场景。

初始实现代码 #

library(tidyr)

testDF <- 
  data.frame(
    ID = as.numeric(c(rep(1,5),rep(50,3),rep(60,3))),
    Period_1 = as.numeric(c(1:5,1:3,1:3)),
    Period_2 = c("2012-06","2012-07","2012-08","2012-09","2012-10","2013-06","2013-07","2013-08","2012-01","2012-02","2012-03"),
    Bal = as.numeric(c(rep(10,5),21:23,36:34)),
    State = c("XX","AA","BB","CC","XX","AA","BB","CC","SS","XX","AA")
  )

testDFextend <- 
  testDF %>%
  tidyr::complete(ID, nesting(Period_1)) %>%
  tidyr::fill(Bal, State, .direction = "down")

testDFextend

编辑：处理跨年度滚动场景 #

为了验证Period_2扩展时的跨年度滚动逻辑，调整Period_2的示例数据，并在原有代码基础上补充跨年度日期生成的逻辑：

改进后完整代码 #

library(tidyr)
library(dplyr)

testDF <- 
  data.frame(
    ID = as.numeric(c(rep(1,5),rep(50,3),rep(60,3))),
    Period_1 = as.numeric(c(1:5,1:3,1:3)),
    Period_2 = c("2012-06","2012-07","2012-08","2012-09","2012-10","2013-06","2013-07","2013-08","2012-10","2012-11","2012-12"),
    Bal = as.numeric(c(rep(10,5),21:23,36:34)),
    State = c("XX","AA","BB","CC","XX","AA","BB","CC","SS","XX","AA")
  )

testDFextend <- 
  testDF %>%
  tidyr::complete(ID, nesting(Period_1)) %>%
  tidyr::fill(Bal, State, .direction = "down")

testDFextend %>% 
  separate(Period_2, into = c("year", "month"), convert = TRUE) %>% 
  fill(year) %>% 
  group_by(ID) %>% 
  mutate(month = sprintf("%02d", zoo::na.spline(month))) %>% 
  unite("Period_2", year, month, sep = "-") %>% 
  # 补充跨年度处理逻辑
  separate(Period_2, into = c("year", "month"), convert = TRUE) %>% 
  mutate(month = as.integer(sprintf("%02d", zoo::na.spline(month)))) %>%
  mutate(year1 = ifelse(month > 12, year+trunc(month/12), year)) %>%
  mutate(month1 = ifelse(month > 12 & month%%12!= 0, month%%12, month)) %>%
  mutate(month1 = ifelse(month1 < 10, paste0(0,month1),month1)) %>%
  unite("Period_2", year1, month1, sep = "-") %>%
  select("ID","Period_1","Period_2","Bal","State")

内容的提问来源于Stack Exchange，提问作者Village.Idyot