Combine several RTF files with different page orientation in R

I am trying to assemble rtf with r2rtf package in R. But it doesn't support different page orientation. If there is other opportunity? I have multiple RTF files which already oriented correctly. They have different headers, footers ect. I just need to assemble them into 1 RTF file with correct orientation and page numbers.

I tried

assemble_rtf(
  input = file,
  output = output,
  landscape = FALSE
)

file - stores paths to my temp separate RTFs output - path to output RTF

consider I have orientation specified for each separate file: rtf_page(orientation = "landscape") or rtf_page(orientation = "portrait")

but in assembled RTF all pages were landscape

I'll use the example from r2rtf::assemble_rtf since you haven't provided any. Before we start, here it is, creating a portrait & a landscape document and merging those:

library(r2rtf)

file <- replicate(2, tempfile(fileext = ".rtf"))
file1 <- head(iris) |>
  rtf_body() |>
  rtf_encode() |>
  write_rtf(file[1])
file2 <- head(cars) |>
  rtf_page(orientation = "landscape") |>
  rtf_body() |>
  rtf_encode() |>
  write_rtf(file[2])
output <- tempfile(fileext = ".rtf")

assemble_rtf(
  input = file,
  output = output
)

This very example suffers from the same problem you have: it comes out as a landscape document. Aside, the landscape= argument of assemble_rtf v1.1.4 does nothing other than being the subject of some input validation, here's the entire source reference for it:

assemble_rtf <- function (input, output, landscape = FALSE)  {
   check_args(landscape, "logical", length = 1)
   ## ..... and nothing else??
}

Anyway, the major issue with the entire package is that they don't use sections which allow different page sizes & orientations, they only use properties that target the entire document at once. Here is a version of assemble_rtf that makes this distinction, I've labelled the changes:

my_assemble_rtf <- function(input, output) {
   input <- normalizePath(input)
   n_input <- length(input)
   missing_input <- input[!file.exists(input)]
   
   if (length(missing_input) > 0) {
      warning("Missing files: \n", paste(missing_input, collapse = "\n"))
      input <- setdiff(input, missing_input)
   }
   
   rtf <- lapply(seq_along(input), \(i) {
      ## Change 1: use \LNDSCPSXN (landscape section)
      ##           rather than \LANDSCAPE (whole document)
      lines <- readLines(input[i]) |>
        stringi::stri_replace_all_regex("\\landscape", "\\lndscpsxn")

      ## Change 2: use section-specific page sizes & margins
      ##           after the first (which will still define the global default)
      if (i > 1) {
         lines <- stringi::stri_replace_all_regex(
                    lines,
                    "\\\\paper(w|h)(?=[^s])",
                    "\\\\pg$1sxn"
                  )
         lines <- stringi::stri_replace_all_regex(
                    lines,
                    "\\\\marg(b|l|t|r)(?=[^s])",
                    "\\\\marg$1sxn"
                  )
      }
      return(lines)
   })
   
   n <- length(rtf)
   start <- c(
     1,
     vapply(rtf[-1], \(x) max(grep("fcharset", rtf[[1]])) + 2, numeric(1))
   )
   end <- vapply(rtf, length, numeric(1))
   end[-n] <- end[-n] - 1
   for (i in seq_len(n)) {
      rtf[[i]] <- rtf[[i]][start[i]:end[i]]
      
      ## Change 3: start a new *section* rather than a new *page*
      ##           after each respective document
      if (i < n)  rtf[[i]] <- c(rtf[[i]], "\n\\pard\n\\sect\n")
   }
   
   rtf <- do.call(c, rtf)
   r2rtf::write_rtf(rtf, output)
}

I should add that this solution is really quite bare-bones because r2rtf apparently creates & assumes very basic RTF structure -- for example that there isn't anything but a fontmap in the header. Still, the principle applies and would require detailed knowledge of your actual RTF structure to further generalize.