On 2025-05-31 7:04 a.m., ravi via R-help wrote:
Hi,
rgl plots seem to require the z object in the form of a matrix. I would like
some help in constructing this matrix when I cannot use the outer function. Let
me explain.
library(rgl)
library(plot3D)
x <- 1:10
y <- 1:20
fun1 <- function (x,y) {x^2+y^2}
z <- outer(x,y, fun1)
open3d()
surface3d(x,y,z,col="red",theta=50, phi=20)
This works fine. However, when I have a data frame of x, y and z with z as a
vector, how do I proceed?
z <- x^2+y^2
surface3d(x,y,z,col="red",theta=50, phi=20)
Error in surface3d(x, y, z, col = "red", theta = 50, phi = 20) :
At least one coordinate must be a matrix
How do I get z in the form of a matrix?
From a private message, it appears you have a scattering of x and y
values, and each has a z. You'd like a plot of the surface z(x, y).
It won't work with your sample data because x and y have different
lengths, but you can do something like this to triangulate your data and
do linear interpolation within each triangle:
x <- runif(100, 0, 10) # 100 random points from 0 to 10
y <- runif(100, 0, 20) # 100 random points from 0 to 20
z <- x^2 + y^2 # z as a function of x and y
library(deldir) # need this to triangulate the x, y values
dxyz <- deldir(x, y, z = z)
library(rgl)
plot3d(dxyz, col = "red")
Use plot3d(dxyz, col = "red", front = "lines") to see the triangulation
more clearly.
Duncan Murdoch
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