R plot (hclust) and clusplot titles cut off on top

Question

I am experiencing the similar problems seen in:

1. Main title at the top of a plot is cut off
2. R: Titles cut in half with par()

and i tried the solutions suggested in both posts.

my code used to plot my hclust:

plot(hclust.train, hang = -1)

here's how my hclust plot look like:

as suggested in the first post mentioned above, i tried:

par(oma=c(0,0,2,0))

to add border padding; however, the plot with the border look like this:

it's simply the cut off version but moved down a bit...

here's how my clusplot plots look like (same problem):

and with the border added:

i've also tried using the argument "mar=c(0,0,2,0)", as suggested in the 2nd post mentioned in the beginning, but the result is the same as adding the border padding.

any help is appreciated.

Edit: Thanks to Ben Bolker for a simple quick solution. After using his suggested code:

par(xpd=NA,oma=c(0,0,2,0))

i got the following improved version:

my last question would be, how to get rid of the border line that's going through the title, OR move the title position above that border line? Thank you!

Answer 1

You didn't give a reproducible example, but I can reproduce this if I set my margins to all-zero; I can work around it with par(xpd=NA)

hc <- hclust(dist(USArrests), "ave")
plot(hc)  ## looks OK

Setting the margins to zero cuts off the title:

par(mar=c(0,0,0,0))
plot(hc)  ## cut off

Setting the outer margin doesn't help:

par(mar=c(0,0,0,0),oma=c(0,0,2,0)) 
plot(hc)

Setting par(xpd=NA) does help:

par(mar=c(0,0,0,0),xpd=NA)
plot(hc)

If I add box() I get a border line that cuts through the title. The best thing would be to not set the margins to zero, or to set par(mar=c(0,0,2,0)) to make sure there's room for the title at the top, or to use par(oma=c(0,0,2,0)) and then use mtext() to add the title by hand.