reorganize folder
diff --git a/R/add_header_above.R b/R/add_header_above.R
new file mode 100644
index 0000000..d3634fa
--- /dev/null
+++ b/R/add_header_above.R
@@ -0,0 +1,103 @@
+#' Add an extra header row above the current header
+#' @export
+add_header_above <- function(kable_input, header = NULL) {
+  kable_format <- attr(kable_input, "format")
+  if (!kable_format %in% c("html", "latex")) {
+    stop("Please specify output format in your kable function. Currently ",
+         "generic markdown table using pandoc is not supported.")
+  }
+  if (kable_format == "html") {
+    return(htmlTable_add_header_above(kable_input, header))
+  }
+  if (kable_format == "latex") {
+    return(pdfTable_add_header_above(kable_input, header))
+  }
+}
+
+# HTML
+htmlTable_add_header_above <- function(kable_input, header = NULL) {
+  if (is.null(header)) return(kable_input)
+  kable_xml <- read_xml(as.character(kable_input), options = c("COMPACT"))
+  # somehow xml2 cannot directly search by name here (it will result in a crash)
+  kable_xml_thead <- xml_child(kable_xml, 1)
+  if (xml_name(kable_xml_thead) != "thead") {
+    kable_xml_thead <- xml_child(kable_xml, 2)
+  }
+
+  header <- standardize_header_input(header)
+
+  header_rows <- xml_children(kable_xml_thead)
+  bottom_header_row <- header_rows[[length(header_rows)]]
+  kable_ncol <- length(xml_children(bottom_header_row))
+  if (sum(header$colspan) != kable_ncol) {
+    stop("The new header row you provided has a different total number of ",
+         "columns with the original kable output.")
+  }
+
+  new_header_row <- htmlTable_new_header_generator(header)
+  xml_add_child(kable_xml_thead, new_header_row, .where = 0)
+  return(structure(as.character(kable_xml), format = "html",
+                   class = "knitr_kable"))
+}
+
+standardize_header_input <- function(header) {
+  header_names <- names(header)
+
+  if (is.null(header_names)) {
+    return(data.frame(header = header, colspan = 1, row.names = NULL))
+  }
+
+  names(header)[header_names == ""] <- header[header_names == ""]
+  header[header_names == ""] <- 1
+  header_names <- names(header)
+  header <- as.numeric(header)
+  names(header) <- header_names
+  return(data.frame(header = names(header), colspan = header, row.names = NULL))
+}
+
+htmlTable_new_header_generator <- function(header_df) {
+  header_items <- apply(header_df, 1, function(x) {
+    paste0('<th style="text-align:center;" colspan="', x[2], '">',
+           x[1], '</th>')
+  })
+  header_text <- paste(c("<tr>", header_items, "</tr>"), collapse = "")
+  header_xml <- read_xml(header_text, options = c("COMPACT"))
+  return(header_xml)
+}
+
+# Add an extra header row above the current header in a LaTeX table ------
+pdfTable_add_header_above <- function(kable_input, header = NULL) {
+  table_info <- magic_mirror(kable_input)
+  header <- standardize_header_input(header)
+  hline_type <- switch(table_info$booktabs + 1, "\\\\hline", "\\\\toprule")
+  out <- sub(hline_type,
+             paste0(hline_type, "\n",
+                    pdfTable_new_header_generator(header, table_info$booktabs)),
+             as.character(kable_input))
+  out <- structure(out, format = "latex", class = "knitr_kable")
+  return(out)
+}
+
+pdfTable_new_header_generator <- function(header_df, booktabs = F) {
+  if (booktabs) {
+    header_df$align <- "c"
+  } else {
+    header_df$align <- "|c|"
+    header_df$align[1] <- "c|"
+    header_df$align[nrow(header_df)] <- "|c"
+  }
+  header_items <- apply(header_df, 1, function(x) {
+    # if(x[2] == 1) return(x[1])
+    paste0('\\\\multicolumn{', x[2], '}{', x[3], '}{', x[1], "}")
+  })
+  header_text <- paste(paste(header_items, collapse = " & "), "\\\\\\\\")
+  cline_end <- cumsum(header_df$colspan)
+  cline_start <- c(0, cline_end) + 1
+  cline_start <- cline_start[-length(cline_start)]
+  cline_type <- switch(booktabs + 1, "\\\\cline{", "\\\\cmidrule(l{2pt}r{2pt}){")
+  cline <- paste0(cline_type, cline_start, "-", cline_end, "}")
+  cline <- cline[trimws(header_df$header) != ""]
+  cline <- paste(cline, collapse = " ")
+  header_text <- paste(header_text, cline)
+  return(header_text)
+}