Split string by words in R

Question

I would like to split a string by two words:

s <- "PCB153 treated HepG2 cells at T18"
strsplit(s, split = <treated><at>)

What should I write instead of <>?

I would get:

"PCB153" "HepG2 cells" "T18"

Answer 1

strsplit(s, split="treated|at")
#[[1]]
#[1] "PCB153 "       " HepG2 cells " " T18" 

Answer 2

You have to enter it as a string. To split on treated:

s <- "PCB153 treated HepG2 cells at T18"
s2 <- strsplit(s,split="treated")
unlist(s2)

To split on treated and at:

unlist(strsplit(unlist(s2),split="at"))