I'd like to add a secondary set axes to ggbiplot; The points and the arrows have, in my case (and probably in many others), huge scale difference. I'd like the points to have one set x and y labels (say bottom(x) and left(y)) that will represent the values of PC1 and PC2 and the arrows will have a different x and Y (say top(x) side of the plot and right(y)), similar to how biplot does it. Any suggestions.
Thanks a lot, Guy