Use gplot() on a factor object

USAGE:

gplot.factor(x, y, se.y, xlab, ylab, residuals, rug, scale, se, xlim, ylim, 
             fit,  ...) 

This is a method for the function gplot() for objects inheriting from class factor. See gplot or gplot.default for the general behavior of this function and for the interpretation of x, y, se.y, xlab, ylab, residuals, rug, scale, se.