[R] display double dot over character in plotmath?

[David Winsemius]

> On May 14, 2017, at 8:43 AM, Ranjan Maitra <maitra at email.com> wrote:
> 
> Thanks, Duncan!
> 
> This works for the particular case and is, to my mind, a great solution!
> 
> However, I was wondering: is it possible to use these double dots with another character, such as omega?  
> 
> I apologize for changing the question somewhat, but I did not realize earlier that there were separate codes for putting double dots over different letters and I thought that figuring out the simpler question would be enough for me to figure out the next step. 

I think you should be looking for a LaTeX solution. There is a tikzDevice-package.

This says you can assemble symbols with backspaces:

https://www.stat.berkeley.edu/~partha/symbols.pdf

For instance, LATEX defines \hbar (“~”) as a “¯” character (\mathchar’26) followed by a backspace of 9 math units (\mkern-9mu), followed by the letter “h”:

The second example in ?tikz, which could be a starting point for completing your task fails on my Mac by only displaying the names of the glyphs but not the glyphs themselves in the plot,  but it might have a better chance of succeeding on a Linux box.

Best;
David.


> 
> Thanks again!
> 
> Best wishes,
> Ranjan
> 
> 
> 
> On Sun, 14 May 2017 23:57:50 +1000 Duncan Mackay <dulcalma at bigpond.com> wrote:
> 
>> Hi
>> 
>> I just had to do something similar in windows with \"{u}. Try Unicode symbol
>> - see ?plotmath 
>> 
>> ggplot(data, aes(x=X)) + geom_line(aes(y = Z), size=0.43) +
>> xlab(expression(atop(top,bold(Age~"\u00e4"))))
>> 
>> Regards
>> 
>> Duncan
>> 
>> Duncan Mackay
>> Department of Agronomy and Soil Science
>> University of New England
>> Armidale NSW 2351
>> Email: home: mackay at northnet.com.au
>> 
>> -----Original Message-----
>> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Ranjan
>> Maitra
>> Sent: Saturday, 13 May 2017 22:48
>> To: r-help at stat.math.ethz.ch
>> Subject: Re: [R] display double dot over character in plotmath?
>> 
>> On Fri, 12 May 2017 23:39:14 -0700 Daniel Nordlund <djnordlund at gmail.com>
>> wrote:
>> 
>>> 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.
>>> 
>>> 
>> 
>> I am sorry, I use a linux operating system. I use Fedora 25 but the student
>> I wanted to show this uses Ubuntu, though I don't know if the distribution
>> matters.
>> 
>> Thanks again for your help, and best wishes,
>> Ranjan
>> 
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>> ______________________________________________
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> 
> 
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> ______________________________________________
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David Winsemius
Alameda, CA, USA