afltables_scrape.R

ScrapeAFLTablesSeasonFixture <- function(season) {
  
  # Requires tidyverse and rvest packages to be loaded
  require(tidyverse)
  require(rvest)
  
  # Scrapes from AFL Tables website
  base.url <- "https://afltables.com/afl/seas/"
  url.extn <- ".html"
  url <- paste0(base.url, season, url.extn)
  
  # Collect raw HTML "soup" that is the webpage and extract the tables that contain fixture content only
  soup <- read_html(url)
  relevant.html.tables <- soup %>% html_nodes("body center > table")
  
  # Blank data frame to fill with fixture
  fixture <- 
    data.frame(
      rnd = integer(), 
      game = integer(), 
      team.home = character(), 
      team.away = character(), 
      ground = character(), 
      stringsAsFactors = FALSE
    )
  
  # Outer loop through rounds in season (regular season only)
  rnd <- 1
  repeat {
    
    # Parse out "Round xx" string using CSS selctors, stop when encounter something other than "Round" heading
    rnd.str <- 
      relevant.html.tables %>% 
      .[[2*rnd-1]] %>% 
      html_nodes("b:nth-of-type(1)") %>% 
      html_text() %>% 
      .[1]
    if (rnd.str %>% pmatch("Round", .) %>% is.na()) {
      break
    }
    
    # Inner loop through games in round
    game <- 1
    repeat {
      
      # Parse out game details from table below the "Round xx" header table, stop when empty string returned
      game.str.raw <- 
        relevant.html.tables %>% 
        .[[2*rnd]] %>% 
        html_nodes("table") %>% 
        .[[game]] %>% 
        html_nodes("a") %>% 
        html_text()
      if (game.str.raw %>% is_empty()) {
        break
      }
      
      # Check for byes (string length == 1) and ignore, parse out home/away team and ground, add observation to fixture data frame
      if (length(game.str.raw) > 1) {
        team.home <- game.str.raw[1]
        ground <- game.str.raw[2]
        team.away <- game.str.raw[3]
        game.row <- 
          data.frame(
            rnd = rnd, 
            game = game,
            team.home = team.home,
            team.away = team.away,
            ground = ground,
            stringsAsFactors = FALSE
          )
        fixture <- rbind(fixture, game.row)
      }
      
      # Increment game counter for the round
      game <- game + 1
    }
    
    # Increment round counter for the season
    rnd <- rnd + 1
  }
  
  # Return the scraped fixture for the season
  fixture
  
}


ScrapeAflTablesLadder <- function(season) {
  
  # Requires tidyverse and rvest packages to be loaded
  require(tidyverse)
  require(rvest)
  
  # Scrapes from AFL Tables website
  base.url <- "https://afltables.com/afl/seas/"
  url.extn <- ".html"
  url <- paste0(base.url, season, url.extn)
  
  # Collect raw HTML "soup" that is the webpage and extract the tables that contain fixture content only
  soup <- read_html(url)
  # ladder.table.rows <- soup %>% html_nodes(".sortable > tbody > tr")
  ladder.matrix <- 
    soup %>%
      html_nodes(".sortable > tbody td") %>% 
      html_text(trim = TRUE) %>%
      matrix(nrow = 18, byrow = TRUE)
  
  colnames(ladder.matrix) <-
    c(
      "ladder.posn",
      "team",
      "played",
      "won",
      "drawn",
      "lost",
      "home.record",
      "away.record",
      "goals.behinds.for",
      "score.for",
      "goals.behinds.against",
      "score.against",
      "percentage",
      "prem.pts"
    )
  
  ladder.data <- 
    ladder.matrix %>% 
    as_tibble() %>%
    dplyr::select(
      team, 
      played, 
      won, 
      lost,
      drawn, 
      prem.pts,
      score.for, 
      score.against, 
      ladder.posn
    ) %>%
    type_convert(
      col_types = cols(
        drawn = col_double()
      )
    ) %>%
    replace_na(list(drawn = 0)) %>%
    mutate(percentage = score.for / score.against * 100) %>%
    mutate(team = map_chr(team, ~team.dictionary[[.]])) %>%
    as.data.frame()
    
}