adds functions for reading excel sheets and writing them as csv into …

…a destination folder

R/excel.R

@@ -0,0 +1,71 @@
+#' Reads all sheets from an excel xlsx file into a list
+#'
+#' @param file file name
+#' @param ... args passed to openxlsx::readWorkbook
+#'
+#' @return a list of data.frames
+#' @export
+excel_worksheets <- function(file, ...) {
+
+  if (!requireNamespace("openxlsx")) stop("openxlsx package required!")
+
+  wb <- openxlsx::loadWorkbook(file)
+  sh_names <- openxlsx::sheets(wb)
+
+  sheets <- 
+    lapply(
+      X   = sh_names, 
+      FUN = openxlsx::readWorkbook, 
+      # arguments passed to readWorkbook
+      xlsxFile = wb, 
+      ...
+    )
+  names(sheets) <- sh_names
+
+  return(sheets)
+}
+
+
+#' Reads all sheets from an excel xlsx file into a list
+#'
+#' @param file file name
+#'
+#' @export
+excel_worksheets_readxl <- function(file) {
+
+  if (!requireNamespace("readxl"))   stop("readxl package required!")
+  sh_names <- readxl::excel_sheets(path = file)
+
+  sheets <- lapply(sh_names, readxl::read_xlsx, path = file, col_types = "text")
+  names(sheets) <- sh_names
+
+  return(sheets)
+}
+
+
+#' Writes list of data.frames as csv files into a folder
+#'
+#' @param sheets a list of data.frames
+#' @param path path to a destination dir
+#' @param ... args passed to fwrite
+#' @export
+worksheets_to_csvs <- function(sheets, path, ...) {
+  if (!requireNamespace("data.table")) stop("data.table package required!")
+  stopifnot(is.list(sheets))
+
+  sh_names <- names(sheets)
+  if (is.null(sh_names)) sh_names <- seq_along(sheets)
+
+  invisible(
+    sapply(sh_names, 
+           function(s) {
+             if (!is.null(sheets[[s]])) {
+               data.table::fwrite(
+                 x    = sheets[[s]],
+                 file = file.path(path, paste0(s, ".csv")), 
+                 ...)
+             }
+         })
+  )
+
+}