R/wiki_didyouknow.R

In wikifacts: Get Facts and Data from Wikipedia and Wikidata

#' Generate 'did you know' facts from the Wikipedia main page on a specified date.
#'
#' @description
#' `wiki_didyouknow()` generates 'did you know' facts from the Wikipedia main page on a specified date.
#'
#' @param n_facts An integer determining the number of facts that will be generated, up to a limit of the maximum facts for the date specified.
#' @param date A date string of the form YYYY-MM-DD.  Default value is a random date since 1 January 2015.
#' @param bare_fact Logical.  Determining whether the fact should be quoted as is or surrounded by a preamble and courtesy statement.
#'
#' @return A vector of strings with random 'did you know' facts from Wikipedia's main page if it exists for the date specified - otherwise "I got nothin'"
#'
#' @examples
#' wiki_didyouknow(n_facts = 2, date = '2020-05-02')


wiki_didyouknow <- function(n_facts = 1L, date = sample(seq(as.Date("2015-01-01"), Sys.Date() - 1, by = "day"), 1), bare_fact = FALSE) {

  locale <- Sys.getlocale("LC_TIME")

  if (.Platform$OS.type == "windows") {
    invisible(Sys.setlocale("LC_TIME", "English"))
  } else {
    invisible(Sys.setlocale("LC_TIME", "en_US.UTF-8"))
  }

  # get url from input and read html
  date <- as.Date(date)
  date1 <- format(date, "%Y_%B_")
  date2 <- gsub("^0+", "", format(date, "%d"))
  date_str <- paste0(date1, date2)

  invisible(Sys.setlocale("LC_TIME", locale))

  input <- paste0("https://en.wikipedia.org/wiki/Wikipedia:Main_Page_history/", date_str)

  tryCatch({
    input <- url(input, "rb")
    wiki_page <- xml2::read_html(input, fill = TRUE)
    close(input)

    # scrape list data
    dyk <- wiki_page %>%
      rvest::html_nodes(xpath = '//*[@id="mp-dyk"]') %>%
      rvest::html_nodes("li") %>%
      rvest::html_text() %>%
      subset(grepl("... that", .))

    n <- min(n_facts, length(dyk))

    dyk <- dyk[grepl("... that", dyk)] %>%
      sample(n)

    if (bare_fact == TRUE) {
      dyk
    } else {
      paste0("Did you know ", gsub("\\.\\.\\. ", "", dyk), " (Courtesy of Wikipedia)")
    }
  },
  error = function (e) {"I got nothin'"},
  warning = function (w) {"I got nothin'"})

}