Epifunky Epifunky - 13 days ago 6
R Question

How to customize notches in ggplot box plot after having setting them manually with ggplot_build ()?

I've got a question relative to this one about how to customize notches in ggplot boxplot. The question's author replied to himself and gave a hint with ggplot_build() but I'm unfortunately not able to use it.

So my question is: once you set manually your notch limits with ggplot_build(), how one reuses it to customize its own box plot?

Here is my data

vib = c(3.94,-0.61,0.03,0.46)
pla = c(0.784444444, 1.11,-1.98,-1.39)

df = data.frame(value = c(vib, pla),
group = c(rep("vibration", times = 4), rep("placebo", times = 4)))

p <- ggplot(df, aes(x = group, y = value)) + geom_boxplot(notch=TRUE)

gg <- ggplot_build(p)

gg$data[[1]]$notchlower[1]<-sort(vib)[qbinom(c(.25, .975), length(vib), .5)][1]
gg$data[[1]]$notchlower[2]<-sort(pla)[qbinom(c(.25, .975), length(pla), .5)][1]

gg$data[[1]]$notchupper[1]<-sort(vib)[qbinom(c(.25, .975), length(vib), .5)][2]
gg$data[[1]]$notchupper[2]<-sort(pla)[qbinom(c(.25, .975), length(pla), .5)][2]

gg$data[[1]]

ggplot(gg$data[[1]], aes(x = x)) +
geom_boxplot(aes(ymin = ymin, lower = lower, middle = middle, upper = upper, ymax = ymax),
stat = "identity",
notch = TRUE)


And the resulting warning message

Error in ifelse(notch, data$notchlower, NA) : replacement has length zero
In addition: Warning message:
In rep(yes, length.out = length(ans)) :
'x' is NULL so the result will be NULL


What am I doing wrong?
Thanks a lot

Answer

Use ggplot_gtable to reverse the operation, instead of feeding it into ggplot again:

gg$data[[1]]$notchlower[1:2]<- c(-1,0)
gg$data[[1]]$notchupper[1:2]<- c(0.5, 1)

plot(ggplot_gtable(gg))

enter image description here