使用R，有人如何计算PDF文件中的页数？

Question

I have about a hundred long PDF files in a directory and would like to know whether R can count how many pages are in each file. My operating system is Windows 8.

Here is the link to a 10-page PDF file, in case this helps you test your solution. MWE pdf file

It appears to be possible to count PDF pages with python, but I don't know that language python solution . Other solutions have been discussed on SO using, eg, Imagemagick. and C##.

Answer 1

I'm working on a Windows 7 machine, but my experiences on Windows 8 make me think it should work just as well for you.

I wasn't able to compile the Rpoppler package, and as hrbrmstr points out, it's probably not worth fighting. If you have 7-Zip, you can extract the poppler tools for Windows. I've extracted them to the location C:\\poppler . Once there, I can do the following

file_name <- "C:/[file_path]/whitepaper-pdfprimer.pdf"

pdf_pages <- function(file_name){
  require(magrittr)
  pages <- system2("C:/poppler/bin/pdfinfo.exe",
                   args = file_name,
                   stdout = TRUE)
  pages[grepl("Pages:", pages)] %>%
    gsub("Pages:", "", .) %>%
    as.numeric()
}

pdf_pages(file_name)

And if you have a vector of file names you want to pass

vapply(file_names, pdf_pages, numeric(1))

Credit to @hrbrmstr for pointing out the poppler tools (I'd never heard of them until today).

Answer 2

On R version 3.3.2 pdftools works:

library(pdftools)
pdfInfo <- pdf_info(<path to PDF file>)
pdfInfo$pages