recurse_html.R

recurse_html.R

library(tibble)
library(purrr)
library(tidyr)
library(htmltools)
library(dplyr)

df <- tibble::tribble(
  ~level_1,   ~level_2,       ~level_3,
  "coffee", "espresso",    "with milk",
  "coffee", "espresso", "without milk",
  "coffee",   "filter",             NA,
     "tea",    "green",             NA,
     "tea",    "black",             NA,
   "water",         NA,             NA
)

nested_df <-
  df |>
  group_by(level_1, level_2) |>
  nest() |>
  group_by(level_1) |>
  nest()

make_html <- function(input) {
  if(is.vector(input) && length(input) == 1 && is.na(input)) return(NULL)
  if (all(is.na(input[,1]))) return(NULL)
  if (ncol(input) == 2) {
    tag(
      "ul",
      pmap(input, function(...) {
        name <- ..1
        data <- ..2
        tagList(
          if (!is.na(name)) tag("li", name) else NULL,
          make_html(data)
        )
      })
    )
  } else {
    lapply(input[,1], \(x) { tag("li", x) })
  }
}

make_html(nested_df)