[R] display double dot over character in plotmath?

Daniel Nordlund djnordlund at gmail.com
Sat May 13 08:39:14 CEST 2017

On 5/12/17 4:55 PM, Ranjan Maitra wrote:
> Hi,
> Is it possible to display double dot (umlaut) over a character such as would be possible using \ddot x in LaTeX? I can do this using tikzDevice but I wanted something simpler to point to.
> Here is an example of what I would like to do, but it is not quite there:
> require(ggplot2)
> data<-as.data.frame(c("a","b","c","a","b","c"))
> colnames(data)<-"Y"
> data$X<-c(1:6)
> data$Z<-c(1,2,3,1,2,3)
> ggplot(data, aes(x=X)) + geom_line(aes(y = Z), size=0.43) + xlab(expression(atop(top,bold(Age~"à"))))
> I would like to put in a double dot over the "a" in the x-axis instead of "`".
> Many thanks for any suggestions and best wishes,
> Ranjan

You haven't told what OS you are using, but with Windows OS, you can get 
the 'ä' by making sure the NUMLOCK key is on, hold down the alt key and 
press 0228 on the numeric keypad.

Hope this is helpful,


Daniel Nordlund
Port Townsend, WA  USA

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