R - 补丁中的3d图

Question

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

Answer 1

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.