extract words in between two commas in R

Question

I have the following string

word <- 'Fu Tien Mansion, Taikoo Shing, Hong Kong'

and I want to extract the word in between the two commas and concatenate it with the first word, what regex to use?

Desired output:

'Taikoo Shing Fu Tien Mansion' 

Answer 1

We can use sub to capture substrings as a group and in the replacement use backreferences of that group

sub("^([^,]+),\\s*([^,]+),.*", "\\2 \\1", word)
#[1] "Taikoo Shing Fu Tien Mansion"

Answer 2

> x <- strsplit(word, ",")[[1]]
> paste(x[2], x[1])
[1] " Taikoo Shing Fu Tien Mansion

Answer 3

sapply(word, function(w){
    ind = gregexpr(",", w)[[1]]
    paste(substring(w, ind[1] + 2, ind[2] - 1),
          substring(w, 1, ind[1] - 1))
})
#Fu Tien Mansion, Taikoo Shing, Hong Kong 
#          "Taikoo Shing Fu Tien Mansion" 

Answer 4

You can also use sapply with strsplit -

> paste(trimws(sapply(strsplit(word,","), `[`, 2)), trimws(sapply(strsplit(word,","), `[`, 1)))
[1] "Taikoo Shing Fu Tien Mansion"