Extract String Between Two words in R

Question

Let's say this is my string

string<- c("righttoleftrightandleft")

I want to extract all the character between right and left so the result will be something like that

results<-("to","and")

Answer 1

string<- c("righttoleftrightandleft")
vec <- strsplit(string, split = "left")

result <- c( sub(pattern = "right", "", vec[[1]][1:2]) )

Answer 2

Please try this with s <- "righttoleftrightandleft"

strsplit(gsub("right(.*?)left", "\\1 ", s), split="\\s")[[1]]

This gives a vector:

[1] "to"  "and"

Note that:

1. gsub extracts all elements between parentheses, each stored in \\\\1
2. ? is required for non-greedy match
3. strsplit splits the resulting match on whitespace

Answer 3

Could try:

gsub("right(.*?)left", "\\1", regmatches(string, gregexpr("right(.*?)left",string))[[1]])

Where regmatches(...) returns matches sequences and gsub(...) extracts the word in the middle.

Answer 4

You can also use the following:

text="righttoleftrightandleft"
A=unlist(strsplit(text,"right|left",))
A[A!=""]
[1] "to"  "and"