绑定和匹配data.frame结构

Question

由于我是data.table包的新手，我想将通常在下面的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"
  }

因此，如果我将Dta和Dtb作为data.table结构，那将是什么路呢？（注意：在实际示例中，我大约有1000万行，因此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)

Answer 1

我们可以使用联接on thee'Custumer'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"][]