Dataframe 为每个姓名添加2000-2008年期间缺失的所有月份

例如：

data <- data.frame(Name = c(rep("A",25), rep("B",50)),
               Date = seq(as.Date("2018-01-01"), as.Date("2020-01-12"), by = 10),
               C1 = rep(c(100,NA,NA,NA,NA,500,320,102,412,NA,200,NA,145,800,230),5),
               C2 = rep(c(100,NA,NA,NA,NA,500,320,102,412,NA,200,NA,145,800,230),5)*2)

---

数据您可以使用
tidyr:：complete
确保将2000-2008年的每个月都包含在您的数据中

解决办法可以是：

library(tidyverse)
library(lubridate)
df %>% mutate(Date = ymd(Date), C2 = C1*2) %>% 
  group_by(Name, YearMon = format(Date, "%Y-%m")) %>%
  summarise_at(vars(starts_with("C")), median, na.rm=TRUE) %>%
  complete(YearMon = 
         format(seq(ymd("2001-01-01"), ymd("2008-12-31"), by="1 month"),"%Y-%m")) %>% 
  as.data.frame()

#     Name YearMon  C1  C2
# 1      A 2001-01  NA  NA
# 2      A 2001-02  NA  NA
# 3      A 2001-03  NA  NA
# 4      A 2001-04  NA  NA
# 5      A 2001-05  NA  NA
# .............
# .............
# 180    B 2007-12  NA  NA
# 181    B 2008-01   4   8
# 182    B 2008-02  11  22
# 183    B 2008-03  13  26
# ............
# ..............

您可以使用
tidyr:：complete
确保在您的数据中包含从
2000年到2008年的每个月

解决办法可以是：

library(tidyverse)
library(lubridate)
df %>% mutate(Date = ymd(Date), C2 = C1*2) %>% 
  group_by(Name, YearMon = format(Date, "%Y-%m")) %>%
  summarise_at(vars(starts_with("C")), median, na.rm=TRUE) %>%
  complete(YearMon = 
         format(seq(ymd("2001-01-01"), ymd("2008-12-31"), by="1 month"),"%Y-%m")) %>% 
  as.data.frame()

#     Name YearMon  C1  C2
# 1      A 2001-01  NA  NA
# 2      A 2001-02  NA  NA
# 3      A 2001-03  NA  NA
# 4      A 2001-04  NA  NA
# 5      A 2001-05  NA  NA
# .............
# .............
# 180    B 2007-12  NA  NA
# 181    B 2008-01   4   8
# 182    B 2008-02  11  22
# 183    B 2008-03  13  26
# ............
# ..............