regex - Remove repeated elements in a string with R

Question

I plan to remove repeated elements (each containing two or more characters) from strings. For example, from "aaa" I expect "aaa", from "aaaa" I expect "aa", from "abababcdcd" I epxect "abcd", from "cdababcdcd" I expect "cdabcd".

I tried gsub("(.{2,})\1+","\1",str). It works in cases 1-3, but fails in case 4. How to solve this problem?

Answer 1

As easy as: gsub("(.{2,})\1+","\1",str, perl = T)