Is it possible to install pandoc on windows using an R command? - r

Question

I would like to download and install pandoc on a windows 7 machine, by running a command in R. Is that possible?
(I know I can do this manually, but when I'd show this to students - the more steps I can organize within an R code chunk - the better)

Answer 1

What about simply downloading the most recent version of the installer and starting that from R:
a) Identify the most recent version of Pandoc and grab the URL with the help of the XML package:
library(XML)
page <- readLines('http://code.google.com/p/pandoc/downloads/list', warn = FALSE)
pagetree <- htmlTreeParse(page, error=function(...){}, useInternalNodes = TRUE, encoding='UTF-8')
url <- xpathSApply(pagetree, '//tr[2]//td[1]//a ', xmlAttrs)[1]
url <- paste('http', url, sep = ':')
b) Or apply some regexp magic thanks to #G.Grothendieck instead (no need for the XML package this way):
page <- readLines('http://code.google.com/p/pandoc/downloads/list', warn = FALSE)
pat <- "//pandoc.googlecode.com/files/pandoc-[0-9.]+-setup.exe"
line <- grep(pat, page, value = TRUE); m <- regexpr(pat, line)
url <- paste('http', regmatches(line, m), sep = ':')
c) Or simply check the most recent version manually if you'd feel like that:
url <- 'http://pandoc.googlecode.com/files/pandoc-1.10.1-setup.exe'
Download the file as binary:
t <- tempfile(fileext = '.exe')
download.file(url, t, mode = 'wb')
And simply run it from R:
system(t)
Remove the needless file after installation:
unlink(t)
PS: sorry, only tested on Windows XP