I know from the R documentation that the gsub function can be programmed to do simultaneous operations like upper/lowercase substitution:

gsub("([a-z]*)([A-Z]*)", "\U\1\L\2", "upper LOWER", perl=TRUE)

[1] "UPPER lower"

I have a minimal example, a string “STTS”, in which I want to replace “S” with “TRUE” and “T” with “FALSE”. I cannot do it sequentially because the matching patterns would obviously collide.

I have tried this code:

gsub("([S]*)\1([T]*)\2", "TRUE \1FALSE \2", "STTS",perl=TRUE)

and received [1] "TRUE FALSE STRUE FALSE TSTRUE FALSE "

instead of "TRUE FALSE FALSE TRUE"