stat_density2d(mapping = NULL, data = NULL, geom = "auto",
position = "identity", na.rm = FALSE, contour = TRUE, n = 100, ...)aes or aes_string. Only
needs to be set at the layer level if you are overriding
the plot defaults.FALSE (the default), removes
missing values with a warning. If TRUE silently
removes missing values.TRUE, contour the results of the
2d density estimationkde2dgeom_density2d