Replace fourth occurrence of a character in a string

Question

I was trying to replace fourth occurrence of '_' in a string. For example,

Input

AAA_BBB_CCC_DD_D_EEE

Output

AAA_BBB_CCC_DDD_EEE

Can anyone please suggest a solution?

Answer 1

You could use a back-reference....

gsub( "(_[^_]+_[^_]+_[^_]+)_" , "\\1" , x )
# [1] "AAA_BBB_CCC_DDD_EEE"

EDIT And thanks to @SonyGeorge below this could be further simplified to:

gsub( "((_[^_]+){3})_" , "\\1" , x )