在 data.frame 结构中 cbind 和 match

Question

由于我是 data.table 包的新手，我想将我通常在下面的 data.frame 结构中执行的操作复制到 data.table 结构中。

Dta     <- data.frame(Customer = c("Javier","Oscar","Ivan","Peter"),Type_of_Customer=LETTERS[c(1,1:3)])
Dtb     <- data.frame(Customer = c("Javier","Oscar","Ivan","Jack"),Zone=5:8,District=100:103)
Result  <- cbind(Dtb[match(Dtb[,"Customer"],Dta[,"Customer"]),c("Zone","District")],Dta)


ww     <- which(is.na(Result[,"Zone"]))
if(length(ww) > 0){
  Result[ww,"Zone"] <- "Not in Dtb"
}

ww     <- which(is.na(Result[,"District"]))
if(length(ww) > 0){
  Result[ww,"District"] <- "Not in Dtb"
  }

所以如果我有 Dta 和 Dtb 作为 data.table 结构，那该怎么办？ （注意：在实际示例中，我有大约 1000 万行，所以我需要更省时的解决方案）

Dta     <- data.table(Custumer = c("Javier","Oscar","Ivan","Peter"),Type_of_Customer=LETTERS[c(1,1:3)])
Dtb     <- data.table(Custumer = c("Javier","Oscar","Ivan","Jack"),Zone=5:8,District=100:103)

谢谢。

Answer 1

我们可以使用连接 onthee 'Customer' 并将 NA 元素替换为 'Not in 'Dtb' 字符串

Dtb[Dta, on = .(Custumer)][, c("Zone", "District") := 
    .(as.character(Zone), as.character(District))
     ][is.na(Zone), c("Zone", "District") := "Not in Dtb"][]
#    Custumer       Zone   District Type_of_Customer
#1:   Javier          5        100                A
#2:    Oscar          6        101                A
#3:     Ivan          7        102                B
#4:    Peter Not in Dtb Not in Dtb                C