I'm attempting to modify how biplot draws its red vectors (among other things). This is how I've started:
Biplot <- function(xx, comps = c(1, 2), cex = c(.6, .4)) { ## Purpose: Makes a biplot with princomp() object to not show arrows ## ---------------------------------------------------------------------- ## Arguments: xx is an object made using princomp() ## ---------------------------------------------------------------------- scores <- xx$scores[, paste("Comp", comps, sep = ".")] loadings <- xx$loadings[, paste("Comp", comps, sep = ".")] plot(range(scores), range(scores), xlab = "", ylab = "", xaxt = "n", yaxt = "n", pch = " ") text(scores[,1], scores[,2], rownames(scores), cex = cex[1]) axis(2) axis(1) } I can make part of a biplot using that function with the USArrests data: Biplot(princomp(USArrests, cor = TRUE), c(1,2), cex = c(.6, .4)) Compare that with what we get using biplot.princomp: biplot(princomp(USArrests, cor = TRUE), c(1,2), cex = c(.6, .4)) It seems to me that the y-values are the same in both plots, but some sort of scaling on the x-axis is happening. Something similar seems to happen with the loadings as well. I notice in the documentation for biplot, mention is made of "... many variations on biplots". Would I be doing something inexcusable if I ignored the differences I've noticed here? TIA -- ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~. ___ Patrick Connolly {~._.~} Great minds discuss ideas _( Y )_ Middle minds discuss events (:_~*~_:) Small minds discuss people (_)-(_) ..... Anon ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~. ______________________________________________ R-help@stat.math.ethz.ch 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.