Unless you want to do this millions of times, efficiecy is probably not a big issue here, but simplicity always pays off.
I'm presuming you are dealing with a single classification setup. Let f (n x 1) be a *factor* defining the classes Let X (n x p) be the data matrix. Then the steps I would use to find the between and within SSP matrices, 'by hand' are as follows: Tot <- scale(X, scale = FALSE) # sweep out the grand means Res <- resid(aov(X ~ f)) # sweep out the class means WSS <- crossprod(Res) # within SSP matrix BSS <- crossprod(Tot - Res) # between SSP matrix Bill Venables CSIRO Laboratories PO Box 120, Cleveland, 4163 AUSTRALIA Office Phone (email preferred): +61 7 3826 7251 Fax (if absolutely necessary): +61 7 3826 7304 Mobile: +61 4 8819 4402 Home Phone: +61 7 3286 7700 mailto:[EMAIL PROTECTED] http://www.cmis.csiro.au/bill.venables/ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, 10 July 2007 9:25 AM To: [email protected] Subject: [R] Within matrix Hi all, I am working on cluster, I am trying to evaluate a within and between matrix. Is there any facility for that ? I did my own function, but I am not a programmer, so I am affraid I am not really able to programme efficiant and fast function... Thanks Christophe ---------------------------------------------------------------- Ce message a ete envoye par IMP, grace a l'Universite Paris 10 Nanterre ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
