从字符串中提取最后的 n 个字符

Question

How can I get the last n characters from a string in R? Is there a function like SQL's RIGHT?

转载于:https://stackoverflow.com/questions/7963898/extracting-the-last-n-characters-from-a-string-in-r

Answer 1

I'm not aware of anything in base R, but it's straight-forward to make a function to do this using substr and nchar:

x <- "some text in a string"

substrRight <- function(x, n){
  substr(x, nchar(x)-n+1, nchar(x))
}

substrRight(x, 6)
[1] "string"

substrRight(x, 8)
[1] "a string"

---

This is vectorised, as @mdsumner points out. Consider:

x <- c("some text in a string", "I really need to learn how to count")
substrRight(x, 6)
[1] "string" " count"