geom that uses hearts instead of points.

geom_heart.r

geom_heart <- function (mapping = NULL, data = NULL, stat = "identity", position = "identity", 
  ..., parse = FALSE, nudge_x = 0, nudge_y = 0, check_overlap = FALSE, 
  na.rm = FALSE, show.legend = NA, inherit.aes = TRUE) 
{
  if (!missing(nudge_x) || !missing(nudge_y)) {
    if (!missing(position)) {
      stop("Specify either `position` or `nudge_x`/`nudge_y`", 
        call. = FALSE)
    }
    position <- position_nudge(nudge_x, nudge_y)
  }
  layer(data = data, mapping = mapping, stat = stat, geom = GeomText, 
    position = position, show.legend = show.legend, inherit.aes = inherit.aes, 
    params = list(parse = parse, check_overlap = check_overlap, 
      na.rm = na.rm, label = sprintf('\u2665'), ...))
}

library(ggplot2)
ggplot(iris, aes(Sepal.Length, Sepal.Width, color = Petal.Length)) +
  geom_heart() +
  scale_color_gradientn(colours = rainbow(5))