> Understood I'd recommend you try to be more precise.
> I just began looking at the volcano dataset which uses geom_contour. The volcano dataset does *not* use geom_contour. However, the help file for the volcano dataset, does use the filled.contour function, in its example. > I now realize that the function stat_density_2d really maps a heatmap If I hadn't read the rest of this thread, I wouldn't know what you meant by "maps" a heatmap. The kde2d function returns a list, containing a density matrix. (As per my previous post). The plotting functions, compute the density via the above density estimation function, and then plot that density, in some form. I suppose you could say the plotting functions map observations to density estimates, then map the density estimates to contours and/or other graphic data, and then map the graphic data to a plot, which is seen by a user... ...but it's probably easier to just say plot the density. >of a computed variable. It's rare in probability theory to refer to density as a "variable". (Which is relevant because density estimates are estimates of probability distributions). However, it is common in computer graphics and geometry, to use "z" for a "third variable". And in applied statistics and data science, "variable" could mean anything... So, be careful there... Based on your posts, I take it you want to plot a function of two variables (or plot a matrix of values), using a 2d plot. There are a number of options here. Contour plots. Filled contour plots. Heatmaps. Plots using hex/other binning. Maybe others...? Additionally, there are 3d plots, such as surface plots. And I note that it's possible to plot contour lines on top of color-filled contours or heatmaps. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.