[R] add symbol above letter in R

[Duncan Murdoch]

On 09/12/2014 2:28 PM, Zilefac Elvis via R-help wrote:
> Hi,
>
> I would like to add a dash (—) on a letter in R.
> How can I add a dash on letter P in the following:
>
> mtext(text=expression(Winter(DJF)~mean~daily~precipitation~italic(P)), side=3, line=1, cex=1.3, col="black")
>
> ?plotmath could not provide an answer to my problem.

But it refers to demo(plotmath), and that's where you could find the 
answer to your question:  use bar().  For example,

mtext(text=expression(Winter(DJF)~mean~daily~precipitation~bar(italic(P))), side=3, line=1, cex=1.3, col="black")

Duncan Murdoch