[R] simplest possible xyz plot

[t takahashi]

New to R, and didn't find the following in the docs.

Main use for R. to get feet wet, is to pipe in x,y,z data, one point
per line, and
plot it in 3d, like this:

{
echo 1,2,3
echo 2,4,6
...
} | R ...

But functions like contour seem to require index vectors that are
sorted.  I am curious why, and how to convert.

Also, I am curious whether any Lisp person has ever written a front
end to R that translates Lisp syntax to R.  e.g. (countour x y f) ->
contour(x,y,f).

Thanks.