R/gs.r

In ropensci/extractr: Extract Text from 'PDFs'

#' PDF-to-text conversion using Ghostscript
#' 
#' Uses a local tool called xpdf at \url{http://www.ghostscript.com/}.
#' 
#' @param files (character) Path to a file, or files on your machine.
#' @param ... Further args passed on to the \code{tm} package, which does the conversion
#' 
#' @author Scott Chamberlain {myrmecocystus@@gmail.com}
#' @return A S3 object of class xpdf with slots for meta and data
#' 
#' @examples \dontrun{
#' path <- "~/github/sac/scott/pdfs/ChamberlainEtal2013Ecosphere.pdf"
#' gs(files = path)
#' 
#' paths <- c("~/github/sac/scott/pdfs/BarraquandEtal2014peerj.pdf", 
#' "~/github/sac/scott/pdfs/Chamberlain&Holland2009Ecology.pdf",
#' "~/github/sac/scott/pdfs/Revell&Chamberlain2014MEE.pdf")
#' res <- gs(files=paths)
#' }

gs <- function(files = NULL, ...) {

  files_exist(files)
  files <- path.expand(files)
  out <- Corpus(URISource(files), readerControl =
            list(reader = readPDF(engine = "ghostscript", control = list(...))))
  meta <- get_meta(out)
  structure(list(meta = meta, data = out), class = "xpdf")
}
# tm:::pdf_text_via_gs(path.expand(paths[1]))