Contours of a 2D density estimate — geom_density_2dPerform a 2D kernel density estimation using MASS::kde2d() and display the results with contours. This can be useful for dealing with overplotting. This is a 2D version of geom_density(). geom_density_2d() draws contour lines, and geom_density_2d_filled() draws filled contour bands. geom_density_2d( mapping = NULL, data = NULL, stat = "density_2d", position = "identity", ..., contour_var = "densit
