Replace last comma in character with " &"

Question

I have many different characters which have the following structure:

# Example
x <- "char1, char2, char3"

I want to remove the last comma of this character with " &", i.e. the desired output should look as follows:

# Desired output
"char1, char2 & char3"

How could I replace the last comma of a character with " &"?

Answer 1

You can use sub :

sub(",([^,]*)$"," &\\1", x)
# [1] "char1, char2 & char3"

Answer 2

One option is stri_replace_last from stringi

library(stringi)
stri_replace_last(x, fixed = ',', ' &')
#[1] "char1, char2 & char3"