I'm trying to project a point into an existing PCOA (Principal Coordinates Analysis) space (in
R). I am under the impression this must be possible, but I can't figure out how to go about it.
Here's how far I've gotten (a toy example):
x <- c(1:10) y <- c(10:1) z <- c(rnorm(10,mean=0,sd=2),rnorm(10,mean=10,sd=2)) m <- cbind(x,y,z) d <- dist(m) r <- pcoa(d) biplot(r,m)
The biplot generates the representation I want. Now, given a new point P=(x,y,z) I would like to project it into the above space. The reason I need this and can't simply add this point to the original matrix is that this new point is going to be an outlier and would change the projection of the original space. What I want is to know where this point ends up relative to the untainted representation.
Also note that I don't actually use a Euclidean distance in reality, so doing a PCA is not an option.