R/openXL.R

In awalker89/openxlsx: Read, Write and Edit XLSX Files

#' @name openXL
#' @title Open a Microsoft Excel file (xls/xlsx) or an openxlsx Workbook
#' @author Luca Braglia
#' @description This function tries to open a Microsoft Excel
#' (xls/xlsx) file or an openxlsx Workbook with the proper
#' application, in a portable manner.
#'
#' In Windows (c) and Mac (c), it uses system default handlers,
#' given the file type.
#' 
#' In Linux it searches (via \code{which}) for available xls/xlsx
#' reader applications (unless \code{options('openxlsx.excelApp')}
#' is set to the app bin path), and if it finds anything, sets
#' \code{options('openxlsx.excelApp')} to the program choosen by
#' the user via a menu (if many are present, otherwise it will
#' set the only available). Currently searched for apps are
#' Libreoffice/Openoffice (\code{soffice} bin), Gnumeric
#' (\code{gnumeric}) and Calligra Sheets (\code{calligrasheets}).
#' 
#' @param file path to the Excel (xls/xlsx) file or Workbook object.
#' @usage openXL(file=NULL)
#' @export openXL
#' @examples
#' # file example
#' example(writeData)
#' #openXL("writeDataExample.xlsx")
#'
#' # (not yet saved) Workbook example
#' wb <- createWorkbook()
#' x <- mtcars[1:6,]
#' addWorksheet(wb, "Cars")
#' writeData(wb, "Cars", x, startCol = 2, startRow = 3, rowNames = TRUE)
#' #openXL(wb)
#' 
openXL <- function(file = NULL){
  
  od <- getOption("OutDec")
  options("OutDec" = ".")
  on.exit(expr = options("OutDec" = od), add = TRUE)
  
  if (is.null(file)) stop("A file has to be specified.")
  
  ## workbook handling
  if ("Workbook" %in% class(file)) {
    file <- file$saveWorkbook()
  }
  
  if (!file.exists(file)) stop("Non existent file or wrong path.")
  
  ## execution should be in background in order to not block R
  ## interpreter
  file <- normalizePath(file)
  userSystem <- Sys.info()["sysname"]
  
  
  if ("Linux" == userSystem ) {
    if (is.null(app <- unlist(options('openxlsx.excelApp')))) {
      app <- chooseExcelApp()
    }
    myCommand <- paste(app, file, "&", sep = " ")
    system(command = myCommand)
    
  } else if ("Windows" == userSystem ){
    shell(shQuote(string = file), wait = FALSE)
    
  } else if ("Darwin" == userSystem){
    myCommand <- paste0("open ", file)
    system(command = myCommand)
    
  } else {
    warning("Operating system not handled.")
  }
  
}


chooseExcelApp <- function() {
  
  m <- c(`Libreoffice/OpenOffice` = "soffice",
         `Calligra Sheets` = "calligrasheets",
         `Gnumeric` = "gnumeric")
  
  prog <- Sys.which(m)
  names(prog) <- names(m)
  nApps <- length(availProg <- prog[ "" != prog])
  
  if (0 == nApps) {
    stop("No applications (detected) available.\n",
         "Set options('openxlsx.excelApp'), instead." )
  } else if (1 == nApps) {
    cat("Only", names(availProg), "found; I'll use it.\n")
    unnprog <- unname(availProg)
    options(openxlsx.excelApp = unnprog)
    invisible(unnprog)
  } else if (1 < nApps) {
    if (!interactive())
      stop("Cannot choose an Excel file opener non-interactively.\n",
           "Set options('openxlsx.excelApp'), instead.")
    res <- menu(names(availProg), title = "Excel Apps availables")
    unnprog <- unname(availProg[res])
    if (res > 0L) options(openxlsx.excelApp = unnprog)
    invisible(unname(unnprog))
  } else {
    stop("Unexpected error.")
  }
}