R/writeRMDKable.R

In MangoTheCat/slideBreakR: Split long tables for presentations

#' rmarkdown Kable Writer
#'
#' Wrapper to `splitTable` that splits a data frame into a a list and 
#' writes out markdown slides to be read in as a child document to 
#' main markdown file
#' 
#' @param df A data.frame to split and write out
#' @param maxRows The maximum number of rows for the new table(s)
#' @param filename The filename of the rmarkdown document including extension.
#' @param slideTitle Slide Title
#' @param otherText Sub text prior to table
#' @param repeatOther Logical. If `TRUE` the sub text will be repeated on each slide
#' @param silent Logical. If `TRUE` reporting of the filename is suppressed.
#' @param ... Other arguments to `kable`
#' 
#' @return Nothing in R.  A markdown document with the specified file name
#' 
#' @export
#' 
#' @examples {
#'   writeRMDKable(airquality, maxRows = 50, slideTitle = "Slide title", 
#'                 otherText = "Extra information")
#'   writeRMDKable(airquality, maxRows = 50, slideTitle = "Slide title", 
#'                 otherText = "Extra information",
#'                 col.names = names(airquality))
#' }
writeRMDKable <- function(df, 
                          maxRows = 50, 
                          filename = tempfile(), 
                          slideTitle = "Table",
                          otherText = NULL, 
                          repeatOther = TRUE, 
                          silent = TRUE, 
                          ...){
  # Start new file
  sink(filename)
  
  # Write out section heading
  cat("#", slideTitle, "\n\n")
  if (!is.null(otherText)) cat(otherText, "\n\n")
  cat("```{r, echo=FALSE, results='asis'}\n")
  
  # Handle other arguments passed to kable
  ellipsis <- list(...)
  otherArgs <- NULL
  if(length(ellipsis) > 0){
    otherArgs <- paste(names(ellipsis), "=", ellipsis, collapse = ",")
    otherArgs <- paste(",", otherArgs)
  }
  
  # Generate expression then call (for the upcoming loop) and write to Rmd
  splitTableExpr <- paste0("dfList <- splitTable(", deparse(substitute(df)), ", maxRows = ", maxRows, ")\n")
  cat(splitTableExpr)
  eval(parse(text = splitTableExpr))
  cat("```\n\n")
  
  # Loop around each table and write new Rmd piece
  for (i in seq_along(dfList)){
    if(i > 1)  cat("#", slideTitle, "\n\n")
    if (i > 1 & !is.null(otherText) & repeatOther) cat(otherText, "\n\n")
    cat("```{r, echo=FALSE, results='asis'}\n")
    cat("knitr::kable(dfList[[", i, "]], row.names=FALSE", otherArgs, ")\n", sep = "")
    cat("```\n\n")
  }
  
  # No return, close file
  sink()
  if (silent) invisible()
  else{
    cat("File written to: \"", filename, "\"\n", sep = "")
  }
}