Question

string <- c("tyuynmklabcwsqzp")

If my task is to substitute every “abc” with “abc123”, the code is,

gsub("abc", "\\1123", string)

But, if I have to search for “abc” and then replace it with “c123”, then how should I do it? Is there a way to divide the regular expression into parts so that I can have \2 like \1?
If it’s possible, then my command would be,

gsub("abc", "\\2123", string).

Please help.

Answer 1

You can use parentheses to group together parts of a regular expression, subsequently applying a repetition operator or backreference to the matched group.

In your case, try this:

string <- c("tyuynmklabcwsqzp")
gsub("(ab)(c)", "\\2123", string)
# [1] "tyuynmklc123wsqzp"