Replace first occurrence from the end of a string in R

Question

As an example I have this vector

c("qw;erty;qwert;qwe;", "ty;qwert;qw")

How can I use sub function or any other to replace first occurrences of ";" from the end of the line with "\t" so the result will be c("qw;erty;qwert;qwe\t", "ty;qwert\tqw") ?

Answer 1

You can also use stri_replace_last_regex from stringi package.

stringi::stri_replace_last_regex(str1, ";", "\t")

Answer 2

We can try

sub(";([^;]*)$", "\t\\1", str1)
#[1] "qw;erty;qwert;qwe\t" "ty;qwert\tqw"  

data

str1 <- c("qw;erty;qwert;qwe;", "ty;qwert;qw")