[R] persp plot + plotting grid lines

[David Winsemius]

This wiki page has the answer. Draw the plot first to establish the  
coordinate system and create the viewing transformation matrix. Draw  
the grid lines with lines(trans3d()), and then put a:

par(new=T) ... and then redraw the plot over the gridlines.

<http://wiki.r-project.org/rwiki/doku.php?id=tips:graphics- 
base:add_grid>

################
x <- seq(-10, 10, length= 30)
y <- x
f <- function(x,y) { r <- sqrt(x^2+y^2); 10 * sin(r)/r }
z <- outer(x, y, f)
z[is.na(z)] <- 1
op <- par(bg = "white")
  persp(x, y, z, theta = 30, phi = 30, expand = 0.5, col = "lightblue",
       ltheta = 120, shade = 0.75, ticktype = "detailed",
       xlab = "X", ylab = "Y", zlab = "Sinc( r )"
) -> res

for (ix in seq(-10,10, by=5)) lines (trans3d(x=ix, y=seq(-10,10,  
by=5), z= -10, pmat = res),
                                              col = "red", lty="dotted")
for (iy in seq(-10,10, by=5)) lines (trans3d(x=seq(-10,10, by=5),  
y=iy, z= -10, pmat = res),
                                              col = "red", lty="dotted")
for (ix in seq(-10,10, by=5)) lines (trans3d(x=ix, y=10, z=  
seq(-10,10, by=5), pmat = res),
                                              col = "red", lty="dotted")
for (iz in seq(-10,10, by=5)) lines (trans3d(x=seq(-10,10, by=5),  
y=10, z= iz, pmat = res),
                                              col = "red", lty="dotted")
  for (iy in seq(-10,10, by=5)) {lines (trans3d(x=-10, y=iy, z=  
seq(-10,10, by=5), pmat = res),
                                               col = "red",  
lty="dotted")}
  for (iz in seq(-10,10, by=5)) {lines (trans3d(x=-10, y=seq(-10,10,  
by=5), z= iz, pmat = res),
                                               col = "red",  
lty="dotted")}
  par(new=T)
  persp(x, y, z, theta = 30, phi = 30, expand = 0.5, col = "lightblue",
        ltheta = 120, shade = 0.75, ticktype = "detailed",
        xlab = "X", ylab = "Y", zlab = "Sinc( r )")
par(op)
-- 
David Winsemius, MD
Heritage Laboratories
West Hartford, CT

On Mar 14, 2009, at 12:02 PM, Pedro Mardones wrote:

> Dear all;
> Does anyone know how to add grid lines to a persp plot? I've tried
> using lines(trans3d..) but the lines of course are superimposed into
> the actual 3d surface and what I need is something like the plot shown
> in the following link:
> http://thermal.gg.utah.edu/tutorials/matlab/matlab_tutorial.html
> I'll appreciate any ideas
> Thanks
> PM