gsub (r) not replacing pattern"S+U "

Question

I am trying to correct a vector of strings with a for loop, this particular one is no working

gsub("S+U ", "t",  "S+U S+U lag")

I also tried with grepl and it detects S+, +U, but with S+U does not work. Does someone know why does this happen?

score 1 · Answer 1 · answered May 03 '21 at 21:38

We can use fixed as TRUE as + is a metacharacter for one or more. So, in the regex mode, it will search for one or more 'S' followed by an U. Either use fixed = TRUE or escape (\\+) to evaluate literally

gsub("S+U ", "t",  "S+U S+U lag", fixed = TRUE)

score 1 · Answer 2 · answered May 03 '21 at 21:40

1

You should escape + by \\+

> gsub("S\\+U ", "t", "S+U S+U lag")
[1] "ttlag"

or you can enable fixed = TRUE

> gsub("S+U ", "t", "S+U S+U lag", fixed = TRUE)
[1] "ttlag"

answered May 03 '21 at 21:40

ThomasIsCoding

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This answer provides both an explanation (as requested by OP) and two solutions. – Limey May 03 '21 at 21:45
@Limey akrun gives a detailed explanation, not me. – ThomasIsCoding May 03 '21 at 21:47
he’s edited his answer. – Limey May 03 '21 at 22:07

gsub (r) not replacing pattern"S+U "

2 Answers2