Drawing labels on flat section of contour lines in ggplot2

Question

In a previous question, I reproduced a contour plot generated with the fields package, in ggplot2 instead (full example below). The only trouble is, I would like to replicate t

Answer 1

You need to implement the algorithm from here:

https://github.com/wch/r-source/blob/c3ba5b0be36d3a1290e18fe189142c88f1e43236/src/library/graphics/src/plot3d.c#L1668

the function doesn't return any information about the position of the contour labels, it does the actual drawing on the graphics device, so you can't hook it into ggplot. It also knows not to draw the contour line under the label.

Until this is implemented in ggplot, stick with base graphics.