On May 28, 2011, at 20:08 , Natalie Stephenson wrote: > Hi ... > > Please could you help with probably a very simple problem I have. I'm > completely new to R and am trying to follow a tutorial using R for Force > Distribution Analysis that I got from ... > http://projects.eml.org/mbm/website/fda_gromacs.htm. Basically, the MDS I > preform outputs a force matrix (.fm) from the force simulation I perform. > > Then, this matrix is read into R and prcomp is performed. > > Basically, the tutorial says 'Having run PCA, now is a good time to check the > eigenvalue structure.' although it doesn't mention how I actually go about > doing that with R. Could anyone tell me how I would be able to check the > eigenvalues/eigenvectors?? > > Thanks so much for your help and I'm sorry if this is a stupid question!!
Not particularly, given that you may be missing some basic theory of PCA. Basically, the loadings of a PCA _are_ the eigenvectors, so e.g. plotting the loadings matrix against the variable number or whatever structure you have on them -- if they are spatial ore temporal measurements, plot against space/time. Something like matplot(loadings(pca), type="l") matplot(times, loadings(pca), type="l") could prove useful (the latter case if your data are really short time series). -- Peter Dalgaard Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd....@cbs.dk Priv: pda...@gmail.com ______________________________________________ R-help@r-project.org 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.
