R/fivethirtyeight.R

In TylerGrantSmith/pickem:

fivethirtyeight_nfl_url <- "https://projects.fivethirtyeight.com/2019-nfl-predictions/games/"

get_games <- function(x) {
  dplyr::tibble(DATE =
                  x %>%
                  rvest::html_nodes(".h4") %>%
                  rvest::html_text(),
                GAMES =
                  x %>%
                  rvest::html_nodes(".games-wrap") %>%
                  purrr::map(~
                               rvest::html_nodes(., ".game-body") %>%
                               rvest::html_table())) %>%
    tidyr::unnest(GAMES) %>%
    dplyr::mutate(GAMES = purrr::map(GAMES, ~purrr::set_names(.,"LOGO","TEAM","SPREAD","WIN_PROB","SCORE"))) %>%
    dplyr::mutate(GAMES = purrr::map(GAMES, ~dplyr::select(., TEAM, WIN_PROB, SCORE))) %>%
    dplyr::mutate(GAMES = purrr::map(GAMES, ~dplyr::mutate(.,
                                                           WIN_PROB =
                                                             WIN_PROB %>%
                                                             stringr::str_replace("%", "") %>%
                                                             as.numeric() / 100,
                                                           HOME_OR_AWAY = c("AWAY","HOME")))) %>%
    dplyr::mutate(GAME_ID = row_number()) %>%
    tidyr::unnest(GAMES)
}


#' Extract 538 NFL Prediction Data
#'
#' @return `data.table`
#' @export
get_538_data <- function() {
  nodes <- xml2::read_html(fivethirtyeight_nfl_url) %>% rvest::html_nodes(".week")

  tibble::tibble(
    WEEK =
      nodes %>%
      purrr::map_int(~rvest::html_nodes(.,".h3") %>%
                       rvest::html_text() %>%
                       stringr::str_replace("Week ", "") %>%
                       as.integer()),
    GAMES =
      nodes %>%
      purrr::map(~rvest::html_nodes(.,".day")) %>%
      purrr::map(get_games)) %>%
    tidyr::unnest(GAMES) %>%
    dplyr::mutate(TEAM = TEAM %>% stringr::str_replace_all("\\.","")) %>%
    dplyr::arrange(WEEK, desc(HOME_OR_AWAY), TEAM) %>%
    dplyr::group_by(WEEK) %>%
    dplyr::mutate(NEW_GAME_ID = row_number()) %>%
    dplyr::group_by(WEEK, GAME_ID) %>%
    dplyr::mutate(RESULT = dplyr::case_when(is.na(SCORE) ~ rlang::na_chr,
                                            max(SCORE) == min(SCORE) ~ "TIE",
                                            SCORE == max(SCORE) ~ "WIN",
                                            TRUE ~ "LOSS")) %>%
    dplyr::mutate(NEW_GAME_ID = min(NEW_GAME_ID)) %>%
    dplyr::ungroup() %>%
    dplyr::mutate(GAME_ID = NEW_GAME_ID) %>%
    dplyr::select(-NEW_GAME_ID) %>%
    data.table::as.data.table()
}