On Fri, 8 Jul 2005, K. Steinmann wrote: > Dear R-helpers, > > Using the package Lattice, I performed a PCA.
In my R installation, the function princomp() is contained in the stats package, not lattice (sic!). > For example > pca.summary <- summary(pc.cr <- princomp(USArrests, cor = TRUE)) > > The Output of "pca.summary" looks as follows: > > Importance of components: > Comp.1 Comp.2 Comp.3 Comp.4 > Standard deviation 1.5748783 0.9948694 0.5971291 0.41644938 > Proportion of Variance 0.6200604 0.2474413 0.0891408 0.04335752 > Cumulative Proportion 0.6200604 0.8675017 0.9566425 1.00000000 > > How can I extract the proportion of variance? The standard deviations are in pc.cr$sdev (see also ?princomp), thus the variances are the squared values and the proportions can be computed as pc.cr$sdev^2/sum(pc.cr$sdev^2) and by taking the cumsum() the cumulative proportion can be computed. This is exactly what the the print method for "summary.princomp" objects does (see stats:::print.summary.princomp). Best, Z > Since names(pca.summary) or str(pca.summary) do not contain the proportion of > variance, > it seems I can not use something similar like pca.summary[[2]]$Comp.1[3]. > I can't see how the values are stored. > > > Thanks in advance. > > K. St. > > ______________________________________________ > [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 > ______________________________________________ [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
