Manual scale, used when you want a direct mapping
> colour <- c("red","green","blue","yellow") > qplot(1:4, 1:4, fill=colour, geom="tile")> qplot(1:4, 1:4, fill=colour, geom="tile") + scale_fill_manual()
> > # To get a legend, you also need to supply the labels to > # be used on the legend, and the grob to draw them: > # grob_tile, grob_line, or grob_point > qplot(1:4, 1:4, fill=colour, geom="tile") + scale_fill_manual(labels=letters[1:4], grob="tile", name="trt")
> > # cyl scaled to appropriate size > qplot(mpg, wt, data=mtcars, size = cyl)
> > # cyl used as point size > qplot(mpg, wt, data=mtcars, size = cyl) + scale_size_manual()
>