Adding Points to persp3D plot

Question

I am working on a study comparing differential evolution and particle swarm optimization performance, and I need to be able to add population points onto a 3D plot. I have reviewed Adding points to 3d plot in r, but that solution does not seem to work in my case, and I cannot figure out why. I am taking the well-known G2 function and using persp3D() as follows:

G2 <- function(x) {
    if (x[1] >= 0 & x[1] <= 10 & x[2] >= 0 & x[2] <= 10 &
        x[1] * x[2] >= 0.75 & x[1] + x[2] <= 15) {
        s <- cos(x[1]) ^ 4 + cos(x[2]) ^ 4
        p <- 2 * cos(x[1]) ^ 2 * cos(x[2]) ^ 2
        r <- sqrt(x[1] ^ 2 + 2 * x[2] ^ 2)
        f <- -abs((s - p) / r)
    } else {
        f <- 0
    }
    return(f)
}

x = y = seq(0, 10, .1)
data = data.frame(matrix(nrow = length(x), ncol = length(y)))
names(data) = y
rownames(data) = x

#Fill in data.frame with G2 values
for (i in 1:length(x)) {
    for (j in 1:length(y)) {
        z = G2(c(x[i], y[j]))
        data[i,j] = z
}
}

zlim = -range(data)
z = as.matrix(data)
par(mfrow = c(1, 1))
windows()
library(plot3D)
persp3D(z = -z, xlab = "x1", bty = "bl2",
    ylab = "x2", zlab = "G2", clab = "depth of G2",
    expand = 0.5, d = 2, phi = 20, theta = 30, resfac = 2,
    image = TRUE, 
    contour = list(col = "grey", side = c("zmin", "z")),
    zlim = zlim, colkey = list(side = 1, length = 0.5))

All of this works well, and I get the plot I am looking for. However, when I try to add points, as suggested in the solution referenced above, my 3D plot is regenerated as a plot of just the one red point:

points3D(1, 1, G2(c(1,1)), col = "red", size = 30)

How do I simply add this point to the existing persp3D() plot? Also, can I control where the point is added (meaning to the contour plot or on the 3D image? My intention is to add populations as the algorithms evolve, and create GIFs for easy visualization, but I do not want to get off point, so I am simplifying by just trying to add this one point to the plot. Thank you for any help!

thc · Accepted Answer · 2017-07-14T01:05:37.647

1

Simple fix ;)

points3D(1, 1, G2(c(1,1)), col = "red", size = 30, add=T)

edited Jul 14 '17 at 01:05

answered Jul 13 '17 at 21:44

thc

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Thank you, but in this particular case, when I add this line, the 3D plot re-renders and the point is not visible. I assume it is hidden in the contours of the plot itself. Is there a way to specify that the points be added to the contour plot above, instead of the 3D portion of the plot? If you run my code, you will see what I mean. Thanks! – Sean Sinykin Jul 14 '17 at 00:52
Are you sure? It works for me. I added an arrow to the picture to indicate where the point is. – thc Jul 14 '17 at 01:04
OK, I figured out my confusion. I needed to add "persp3D(x = x, y = y, z = -z,..." in my call to persp3D. I am guessing that the function assumes x = y = [0,1] when x and y are omitted, which is why the dot was there, rather than where I expected it within the plot. After fixing that, I notice that if I add the line points3D(3.6194503, 1.6067539, G2(c(3.6194503, 1.6067539)),col = "red", size = 30, pch = 19, add = T) , the point ends up strangely off of the plot. The point (3.6194503, 1.6067539) should be somewhere in the middle, but does not plot that way. – Sean Sinykin Jul 14 '17 at 03:45
Beyond that issue, I would like to specify that the points be plotted on the contour plot above the 3D plot, if possible. Is there a way to do that? On the 3D plot, the points disappear behind peaks. Thanks! – Sean Sinykin Jul 14 '17 at 03:48

Adding Points to persp3D plot

1 Answers1