I have the following data in a data frame:
**x** in (0,1)
**y** in [0,1]
**z** in [0,1]
For example:
X,Y,Z
0.1, 0.2, 0.56
0.1, 0.3, 0.57
...
I'd like to plot them on this type of chart:
I tried on R, but all I could get was a not-so-fancy 3d scatterplot. I also read about the lattice 3d wireframe, but I couldn't get my head around it.
What am I supposed to do to get a Matlab like wireframe in R? What data transforms are involved?
This is the sample code from the documentation:
x <- seq(-pi, pi, len = 20)
y <- seq(-pi, pi, len = 20)
g <- expand.grid(x = x, y = y)
g$z <- sin(sqrt(g$x^2 + g$y^2))
wireframe(z ~ x * y, g, drape = TRUE,
aspect = c(3,1), colorkey = TRUE)
I don't find it particularly clear.
EDIT: the persp3d
function works fine, and I was able to generate a 3d plot with one colour. How can I set a colour scale relative to the z value?
Thanks for any hints, Mulone
Use outer
to create the z values and then use persp
to plot:
z <- outer(x,y, function(x,y) sin(sqrt(x^2+y^2)))
persp(x,y,z)
There are options for colouring and setting the viewing angle, see ?persp
. See the fourth example for Matlab style colouring.
For an interactive plot, consider using persp3d
in the rgl
package:
require(rgl)
persp3d(x,y,z,col="blue")
Edit
To add colour, there is a slight difference from the method in persp
, since the colour relates to the vertex rather than the centre of the facet, but it makes it easier.
jet.colors <- colorRampPalette( c("blue", "green") )
pal <- jet.colors(100)
col.ind <- cut(z,100) # colour indices of each point
persp3d(x,y,z,col=pal[col.ind])
The help file recommends adding the parameter smooth=FALSE
, but that's down to personal preference.