Question

At present, I generate a figure using the following script

 dat <- matrix(runif(1000*99),99,1000)
 dat <- rbind(rep(0.1,1000),dat)
 out <- cmdscale(dist(dat),k = 2)
 plot(out)
 points(out[1,1],out[1,2],col = "red")

Based on the above figure, I want to connect that red point with other points, how to do that?

Answer 1

If you want to connect all the points to that red point, you could try…

segments(out[1,1],out[1,2],out[,1],out[,2])

Adjusting the order of the printing and the graphical characteristics could make it a little easier to look at too:

dat <- matrix(runif(1000*99),99,1000)
dat <- rbind(rep(0.1,1000),dat)
out <- cmdscale(dist(dat),k = 2)
plot(out,type="n")
segments(out[1,1],out[1,2],out[,1],out[,2],col="#cccccc")
points(out,col="black",pch=20)
points(out[1,1],out[1,2],col = "red",pch=20)