R function to convert all PDFs in a directory into PNGs

convert_pdf_to_png.R

#===============================================================================
# 2023-12-21 -- misc
# convert pdf to png
# Ilya Kashnitsky, [email protected], @ikashnitsky
#===============================================================================


#' @description A function to convert all PDFs in a directory into PNGs
#' @param dir_pdfs character. A character string with a path to the directory containing PDFs to convert
#' @param output_dir character. An optional parameter to specify the output directory for the converted PNGs. Defaults to `"/png"`, which creates a sub-directory `png` in the specified above `dir_pdfs` directory. Can be any location on the machine, one useful place may be something with all the temporary stuff like `"~/Downloads"`. Important: don't leave trailing slashes in the parameters.
convert_pdf_to_png <- function(dir_pdfs, output_dir = "/png") {
  
  require(pdftools)
  require(fs)
  require(magrittr)
  require(stringr)
  require(purrr)
  
  pdfs <- dir_ls(dir_pdfs) %>%
    str_subset(".pdf")
  
  base <- pdfs[1] %>% 
    str_remove("/[^/]+$")
  
  if(output_dir == "/png"){
    
    dir_create(path = paste0(base, "/png"))
    
    convert_one_pdf <- function(path_to_pdf){
      path = path_to_pdf %>% paste
      pdf_convert(
        pdf = path, 
        filenames = path %>% 
          str_remove(base) %>% 
          str_replace(".pdf", ".png") %>% 
          paste0(base, "/png", .), 
        dpi = 300
      )
    }
    
  }else{
    convert_one_pdf <- function(path_to_pdf){
      path = path_to_pdf %>% paste
      pdf_convert(
        pdf = path, 
        filenames = path %>% 
          str_remove(base) %>% 
          str_replace(".pdf", ".png") %>% 
          paste0(output_dir %>% path_expand %>% paste, .), 
        dpi = 300
      )
    }
  }
  
  pdfs %>% map(convert_one_pdf)
  
}