r - ggplot2 - スケールはどこに構築されていますか?

Question

因子の値が数値に変換される場所を確認したかったのです。printどこにでもステートメントを追加するだけでこれを達成しようとしました...

geom_tile2 <- function(mapping = NULL, data = NULL,
                      stat = "identity2", position = "identity",
                      ...,
                      na.rm = FALSE,
                      show.legend = NA,
                      inherit.aes = TRUE) {
  layer(
    data = data,
    mapping = mapping,
    stat = stat,
    geom = GeomTile2,
    position = position,
    show.legend = show.legend,
    inherit.aes = inherit.aes,
    params = list(
      na.rm = na.rm,
      ...
    )
  )
}

GeomTile2 <- ggproto("GeomTile2", GeomRect,
  extra_params = c("na.rm", "width", "height"),

  setup_data = function(data, params) {
    print(data)

    data$width <- data$width %||% params$width %||% resolution(data$x, FALSE)
    data$height <- data$height %||% params$height %||% resolution(data$y, FALSE)

    transform(data,
              xmin = x - width / 2,  xmax = x + width / 2,  width = NULL,
              ymin = y - height / 2, ymax = y + height / 2, height = NULL
    )
  },

  default_aes = aes(fill = "grey20", colour = NA, size = 0.1, linetype = 1,
                    alpha = NA),

  required_aes = c("x", "y"),

  draw_key = draw_key_polygon
)

と

stat_identity2 <- function(mapping = NULL, data = NULL,
                          geom = "point", position = "identity",
                          ...,
                          show.legend = NA,
                          inherit.aes = TRUE) {
  layer(
    data = data,
    mapping = mapping,
    stat = StatIdentity2,
    geom = geom,
    position = position,
    show.legend = show.legend,
    inherit.aes = inherit.aes,
    params = list(
      na.rm = FALSE,
      ...
    )
  )
}

StatIdentity2 <- ggproto("StatIdentity2", Stat,

  setup_data = function(data, params) {
    print(data)
    data
  },
  compute_layer = function(data, scales, params) {
    print(data)
    print("stat end")
    data
  }
)

しかし、例えば実行すると

ggplot(data.frame(x = rep(c("y", "n"), 6), y = rep(c("y", "n"), each = 6)), 
       aes(x = x, y = y)) + 
  geom_tile2()

xとは、 以降の関数の数値yです。パッケージの Github リポジトリを見ると、この座標への変換が実際にどこで行われているのかわかりませんか?setup_datastat