pscategorical {ggplot} | R Documentation |
Add a categorical position scale to the plot
pscategorical(plot = .PLOT, variable="x", name="", expand=c(0.01, 0.6))
plot |
ggplot object |
variable |
axis ("x" or "y") |
name |
name of the scale (used in the legend) |
expand |
expansion vector (numeric vector, multiplicative and additive expansion). Defaults to adding 0.6 on either end of the scale. |
A categorical scale converts a factor into a numerical representation
very simply: by using as.numeric
. This means that levels
will be placed a integer locations in the same order that they
appear in the levels of the factor (see levels
).
If you want to reorder (or combine) categories, currently the best way to do this is to modify the original factors. In a future version of ggplot I will probably expand the categorical scale so that you can do that here.
This scale is added to the plot automatically when you use a categorical variable in the x or y aesthetics. You shouldn't need to to call this function unless (for some reason) you want to change the expansion factor.
Hadley Wickham <h.wickham@gmail.com>
p <- ggpoint(ggplot(mtcars, aesthetics=list(x=cyl, y=mpg))) pscategorical(p, "x") # no change, because already categorical pscategorical(p, "y") # chops into discrete segments