Computation failed in `stat_function()` for non-numeric values of x

[atfg]

Drawing a line with stat_function for x as factor used to work in ggplot2_1.0.0 and ggplot2_1.0.1. Doesn't work in ggplot2_2.0.0:

ggplot(iris,aes(x=factor(Species),Petal.Length)) + geom_violin() + stat_function(fun=function (x) as.numeric(x)^2, colour="red")

This works in ggplot2_2.0.0, but the x labels need fixing:

ggplot(iris,aes(x=as.numeric(Species),Petal.Length,group=as.numeric(Species))) + geom_violin() + stat_function(fun=function (x) as.numeric(x)^2, colour="red")

[klmr]

It’s worth noting that the x labels cannot be fixed by adding a scale_x_discrete — this will result in the same error as when passing a categorical variabel to the function.

However, using a scale_x_continuous works:

ggplot(iris) +
    aes(as.numeric(Species), Petal.Length, group = Species) +
    geom_violin() +
    stat_function(fun = function (x) as.numeric(x) ^ 2, color = "red") +
    scale_x_continuous('Species',
                       breaks = seq_len(nlevels(iris$Species)),
                       labels = levels(iris$Species))