find doi in text and return citation

doi.r

library('stringr')
library('readr')
library('rcrossref')

doiref <- function(path, style = 'apa'){
  mystring <- readr::read_file(path)
  doi <- unlist(stringr::str_extract_all(mystring, "\\b10\\.(\\d+\\.*)+[\\/](([^\\s\\.])+\\.*)+\\b"))
  doi <- unique(doi)
  ref <- vector()
  for (i in 1:length(doi)){
        temp <- try(rcrossref::cr_cn(dois = doi[i], format = "text", style = style), T)
        ref <- c(ref,temp)
  }
  return(ref)
}