R 3d surface plot with factor variables

Question

I have a pretty simple question but just can't get my head around. How do I create a 3D surface plot with grid for the following data.

x = c("Jan","Feb","Mar","Apr","May","Jun")
y = c("2010","2011","2012")
z = matrix(seq(1:18),nrow=3)

I have tried something like this, but still can't get what I want.

persp3d(x, y, z)
plot3d(x, y, z)

Thanks.

Answer 1

The error that persp3d() gives when the x is a factor or character variable means it will only take numeric in x (and probably in y and z too) so x, y must be numeric:

x <- 1:6

Corresponding month names:

month <- c("Jan","Feb","Mar","Apr","May","Jun")

I retract my previous statement here, now that I understand how plot3d maps z-values at positions defined by x and y so y can stay as is, but has to be numeric:

y = c(2010,2011,2012)

In addition, nrow(z) must be the same as nrow(x), again this is clear from the error thrown when one attempts the contrary. So:

z = matrix(seq(1:18),nrow=6)

Plot your surface without the default axes: (from here, the approach is very similar to how we do custom axes with ordinary 2d graphs in R)

library(rgl) persp3d(x, y, z, axes=F, ylab="", zlab="") box3d()

Finally add your axes:

axis3d(edge='x++', at=x, labels=month, tick=T) axis3d(edge='y--', at=y, labels=y, tick=T, pos=c(0,0,0), line=-1) axis3d(edge='z+-', at=as.integer(range(z)), labels=as.integer(range(z)), tick=T)