Its easiest to just check the source. biplot is a generic which calls biplot.princomp which calls biplot.default which in turn calls plot so try this and examine the source:
stats:::biplot.default On 7/31/06, Patrick Connolly <[EMAIL PROTECTED]> wrote: > 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. > ______________________________________________ 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.