On 22/01/2010 8:52 AM, mlcarte3 wrote:
Which line do you want? There's more than one choice. For example, you
could regress y and z on x, or you could find the principle axis of the
x, y, z point cloud.
Duncan Murdoch
Thanks for the response. I need to find the principal axis for the point
cloud. How can I plot this in R?
This will do it:
# Generate some correlated data
x <- matrix(rnorm(3000)+2:4, ncol=3)
y <- x %*% matrix(c(1,-2,3,2,3,4,3,4,4), 3,3)
# Plot it
library(rgl)
plot3d(y)
# Compute the principle components
pc <- princomp(y)
# Plot a line corresponding to the main one
centre <- pc$center
direction <- pc$loadings[,1]
segments3d(rbind(min(pc$scores[,1])*direction + centre,
max(pc$scores[,1])*direction + centre))
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