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Hi! My question(s) in the end might be silly but I am no expert on this, so here it goes: Noy-Meir (1973), Pielou (1984) and a few others have pointed to non-centered PCA being in some cases...

Hi list! I have prepared a custom function (below) in order to calculate separability indices (Divergence, Bhattacharyya, Jeffries-Matusita, Transformed divergene) between two samples of (spectral land cover) classes. I need help to cross-compare results to verify that it...

Christofer Bogaso wrote: > Dear all, I am looking for some interactive study materials on Principal > component analysis. Basically I would like to know what we are actually > doing with PCA? Having in mind the eigenvalue decomposition and a bivariate data...

Nikos: > Hi list! > > I have prepared a custom function (below) in order to calculate > separability indices (Divergence, Bhattacharyya, Jeffries-Matusita, > Transformed divergene) between two samples of (spectral land cover) > classes. I've found a mistake: initially I used "log10" instead...

Peter Ehlers wrote: > Nikos, > > I think you can just replace the line > > pc <- princomp(x[,1:2], scores=TRUE, na.action=na.fail) > > with > > pc <- prcomp(x[,1:2], retx=TRUE, center=pc.center, > scale.=pc.scale, na.action=na...

Dear R-list, Among the (R-)tools, I've seen on the net, for (bivariate) Principal Component scatter plots (+histograms), "plotpc" [1] is the one I like most. By default it performs PCA on a bivariate dataset based on R...

This time with a more-R oriented question: Is the mrpp {vegan} package [1] useful in trying to check, or get a clue about the differences between- and within-axes (or variables or dimensions or columns) of a multivariate matrix...

Nikos: > > I finally ran mrpp tests. I think all is fine but one very important > > issue: I > > have no idea how to export/save an "mrpp" object. Tried anything I > > know and > > searched the archives but found nothing. David W...

On Thu, 2009-11-05 at 01:13 -0800, cremi wrote: > I habe installed ubuntu 9.04 server (powerpc) i want to install an R version > > 2.9.0 to run rmpi. > > When i add the repository to my sources...

On Wednesday 30 of June 2010 23:02:09 afsouza at unisinos.br wrote: > Hi all, > > I am using the vegan package to run a prcincipal components analysis > on forest structural variables (tree density, basal area, average > height, regeneration density...

jim holtman: > You might want to look at how to use 'lapply' to create lists. Here > is one way of doing it: > > > # create test data > > a_threshold <- b_threshold <- as.data.frame(matrix(sample(c(1:5, > NA), 100, TRUE...

Nikos Alexandris: > Among the (R-)tools, I've seen on the net, for (bivariate) Principal > Component scatter plots (+histograms), "plotpc" [1] is the one I like > most. [...] > I started the modification by attempting first to get a "prcomp" version of...

Hi R-list. This is my first post. I'll try to be as precise as possible with the difficulty I have to "get things done". I have a hard time trying to construct a double "for" loop and create...