R plot violin plot or box plot outside of the plot region-CodePudding

Usually, in R, I'm able to use xpd = NA to add elements to an existing plot that extend outside of the plot region.

However, in this case I am trying to add violin plots or box plots, and this approach is not working.

library(vioplot)

# generate some data
dat <- replicate(10, rnorm(20), simplify = FALSE)

range(unlist(dat))

# first example, with all data within range
plot.new()
plot.window(xlim = c(1, 10), ylim = c(-5,5))
axis(1)
axis(2)

vioplot(dat, add = TRUE, frame.plot = FALSE)

Now trying to plot outside of the plotting region.

plot.new()
par(oma = c(3,3,3,3))
plot.window(xlim = c(1, 10), ylim = c(-10, -2))
axis(1)
axis(2)

vioplot(dat, add = TRUE, frame.plot = FALSE, xpd = NA)
boxplot(dat, add = TRUE, frame.plot = FALSE, xpd = NA)

# plot points to prove that this works with some elements
points(1:10, sapply(dat, median), xpd = NA)

Any ideas on how to add violin plots or box plots in such a scenario? With box plots, I could of course easily draw them myself with rect() and segments(), but violin plots are more complicated.

CodePudding user response：

You can set xpd=NA globally with par(xpd=NA), draw what you need with vioplot() or boxplot() and then restore the default xpd value with par(xpd=F).

Looking in the source code, vioplot() ignores all graphical parameters (including xpd) passed to it if they are NA. You could in theory use xpd=T but this is unfortunately not passed to all the lower level drawing functions. boxplot() (or rather its workhorse bxp()) does not seem to pass xpd to any of the drawing functions it uses.