R/listify.R

In RydenButler/labelR: Pairwise Data Labeling with Amazon's Mechanical Turk

#' Format a HTML unordered list
#'
#' \code{listify} reformats list objects as unordered HTML lists.
#'
#' @param nested_list A list object containing a combination of strings or lists.
#' Each string element of the list is reformatted as a bullet in an unordered list.
#' Each list object element is treated as a nested unordered list, which will possess
#' a different bullet type.
#'
#' @details
#' This function is for internal package use. It creates a string in HTML format
#' that renders an unordered list when provided with a \code{list} object.
#'
#' @return An html-formatted list
#'
#' @author Ryden Butler
#'
#' @rdname listify

listify <- function(nested_list) {
  paste(sapply(nested_list, function(x) {
    ifelse(length(x) == 1,
      paste0("<li>", x, "</li>"),
      paste(sapply(x, function(y) {
        ifelse(!is.list(y),
          paste0("<li>", y),
          paste0("<ul>", listify(y), "</ul></li>")
        )
      }), collapse = "")
    )
  }), collapse = "")
}