比较来自不同data.frame的日期

我必须比较两个不同的df中有相同ID的一些日期。 让我在这里提供一个有效的例子：

df1
ID MONTH YEAR
1  1     1997
2  7     2004
3  6     2017
4  8     2003
5  11    1990
6  3     1999

df2
ID MONTH YEAR
1  4     2003
1  8     2006
3  12    2000
4  4     2015
5  1     1993
6  1     1991

正如我们所看到的，我们得到了两个数据帧，其中ID列是共同的，而月份和年份列则标识了一个精确的日期。现在我必须将df2的每一行与df1进行比较，作为输出，让我知道日期是在df1中相同ID之前还是之后。这应该是示例输出：

df3
ID STATUS
1  After
1  After
2  None
3  Before
4  After
5  After
6  Before

我希望我解释得很好

---

非常感谢，Andrea。

您可以使用zoo软件包中的

as.yearmon

，

merge

和

ifelse

library(zoo)
df1$date1  <- as.yearmon(with(df1, paste0(YEAR, "-",MONTH))) #setting date in df1
df2$date2  <- as.yearmon(with(df2, paste0(YEAR, "-",MONTH)))#setting date in df2
tmp <- merge(df1, df2, by="ID", all = TRUE) # combining both data.frames
tmp$STATUS <- ifelse(is.na(tmp$date1)|is.na(tmp$date2), "None",
                     ifelse(tmp$date1 > tmp$date2, "Before", "After")) # doing logical comparison 
df3 <- tmp[, c("ID", "STATUS")] # building desired data.frame
df3
  ID STATUS
1  1  After
2  1  After
3  2   None
4  3 Before
5  4  After
6  5  After
7  6 Before

图书馆（动物园）
df1$date1您可以使用zoo软件包中的
as.yearmon
，
merge
和
ifelse

library(zoo)
df1$date1  <- as.yearmon(with(df1, paste0(YEAR, "-",MONTH))) #setting date in df1
df2$date2  <- as.yearmon(with(df2, paste0(YEAR, "-",MONTH)))#setting date in df2
tmp <- merge(df1, df2, by="ID", all = TRUE) # combining both data.frames
tmp$STATUS <- ifelse(is.na(tmp$date1)|is.na(tmp$date2), "None",
                     ifelse(tmp$date1 > tmp$date2, "Before", "After")) # doing logical comparison 
df3 <- tmp[, c("ID", "STATUS")] # building desired data.frame
df3
  ID STATUS
1  1  After
2  1  After
3  2   None
4  3 Before
5  4  After
6  5  After
7  6 Before

图书馆（动物园）
df1$date1