Samuel Royer Tardif
2010-May-27 14:24 UTC
[R] LDA with unstandardized discriminant functions
Hi, I am currently performing a LDA on soil fatty acid compositions (68 sites, 19 FAs). However, because FAs abundance is caculated in mol% (the molar amount of each FA divided by total molar amount of FAs in the sample), I would like to get unstandardized discriminant functions computed on the original descriptors (see Legendre & Legendre 1998, p.618 for details). How can I do this in R. I've used the function lda(), but the argument scale=FALSE doesn't change anything. Here is an example of my script: #example with 3 variables and 10 sites x1<-rnorm(10,2,1) x2<-rnorm(10,4,2) x3<-rnorm(10,3,2) X<-cbind(x1,x2,x3) group<-c("a","a","a","b","b","b","b","c","c","c") (xlda1<-lda(X,group,scale=TRUE)) (xlda2<-lda(X,group,scale=FALSE)) # It gives the same results Thanks for your help, Samuel Royer Tardif Ph.D student Soil ecology Universit? de Sherbrooke, Qc, Canada _________________________________________________________________ [[elided Hotmail spam]]