R 基于两个数据帧中两个现有列之间的匹配添加和填充新列

我有两个数据帧（df1和df2），其示例如下：

df1 <- data.frame(StationID = c(1,1,1,2,2,3,3,3,3,3),
              Cameras       = c("Cam1","Cam2","Cam2","Cam1","Cam1","Cam2","Cam1","Cam2","Cam1","Cam1"),
              Start         = c("2013-04-23","2013-04-23","2013-04-23","2013-04-23","2013-04-23","2013-04-23","2013-04-23","2013-04-23","2013-04-23","2013-04-23"),
              End           = c("2013-04-25","2013-04-25","2013-04-25","2013-04-25","2013-04-25","2013-04-25","2013-04-25","2013-04-25","2013-04-25","2013-04-25"))


df2 <- data.frame(StationID = c(1,1,2,2,3,3),
                  Cameras   = c("Cam1","Cam2","Cam1","Cam2","Cam1","Cam2"))

df1也许这有帮助

library(dplyr)
library(tidyr)
full_join(df1,df2) %>% group_by(StationID,Cameras) %>% summarise_each(funs(toString)) %>% separate(col = Start,into = paste("Start",1:3,sep=""),sep=", ",extra="merge") %>% separate(col = End,into = paste("End",1:3,sep=""),sep=", ",extra="merge")

我们将“StationID”和“Cameras”上的两个数据集
连接起来，并使用
data.table
中的
dcast
，它可以将多个
value.var
列重塑为“宽”格式

 library(data.table)#1.9.7+
 dcast(setDT(df1)[df2, on = c("StationID", "Cameras")], 
     StationID + Cameras ~rowid(StationID, Cameras), value.var = c("Start", "End"))
 # StationID Cameras    Start_1    Start_2    Start_3      End_1      End_2      End_3
 #1:         1    Cam1 2013-04-23         NA         NA 2013-04-25         NA         NA
 #2:         1    Cam2 2013-04-23 2013-04-23         NA 2013-04-25 2013-04-25         NA
 #3:         2    Cam1 2013-04-23 2013-04-23         NA 2013-04-25 2013-04-25         NA
 #4:         2    Cam2         NA         NA         NA         NA         NA         NA
 #5:         3    Cam1 2013-04-23 2013-04-23 2013-04-23 2013-04-25 2013-04-25 2013-04-25
 #6:         3    Cam2 2013-04-23 2013-04-23         NA 2013-04-25 2013-04-25         NA

注：
rowid
来自数据。表1.9.7。它可以从安装。如果我们有版本1.9.6或更高版本，请通过

 dN <- setDT(df1)[df2, on = c("StationID", "Cameras")
                     ][, rid := 1:.N, .(StationID, Cameras)]

谢谢你的建议。这似乎正是我要找的。然而，当我运行代码时，我得到了以下错误（eval（expr、envir、enclose）中的错误）：找不到函数“rowid”。我做错了什么？我设法让它工作了。我有data.table的CRAN版本，而不是包含rowid函数的开发版本（v.1.9.7）。对于需要访问此版本的用户，只需转到。再次感谢大家的帮助！谢谢你的建议。这似乎在某种程度上起了作用；2号站摄像机2不见了。我想这是因为所有的NA，但是有没有一种方法可以保存df3中的所有记录，包括构成所有NA的记录？Thanks@Ross：补充说。对不起，我没注意到。
 dN <- setDT(df1)[df2, on = c("StationID", "Cameras")
                     ][, rid := 1:.N, .(StationID, Cameras)]

dcast(dN, StationID + Cameras ~rid, value.var = c("Start", "End"))