Determine the Geom from within a Stat

For good reasons(?) within the Grammar of Graphics, the Stat and the Geom should work independently.

For other reasons, I sometimes want to do weird things within a Stat depending on which Geom it is being used with.

Finding the name of the Geom is not obvious, so I’ve included get_geom() which interrogates the frame stack to find the Layer which contains the Stat, and finds the name of the Geom contained within that Layer.

If anyone knows of a better way of doing this, please get in touch!

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Create a Stat to test with
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
stat_oath_breaker <- function(mapping = NULL, data = NULL,
                              geom     = "point",
                              position = "identity",
                              ...,
                              show.legend = NA,
                              inherit.aes = TRUE) {
  layer(
    data        = data,
    mapping     = mapping,
    stat        = StatOathBreaker,
    geom        = geom,
    position    = position,
    show.legend = show.legend,
    inherit.aes = inherit.aes,
    params = list(
      na.rm = FALSE,
      ...
    )
  )
}

StatOathBreaker <- ggproto(
  "StatOathBreaker", Stat,
  
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  # Call `get_geom()` from within the Stat
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  setup_params = function(data, params) {
    message("StatOathBreaker being used with: ", ggdebug::get_geom())
    params
  },
  
  compute_layer = function(data, scales, params) {
    data
  }
)


ggplot(mtcars) +
  geom_line(aes(mpg, wt), stat = 'oath_breaker')

StatOathBreaker being used with: GeomLine