[R] display double dot over character in plotmath?

[Robert Baer]

I got this but the spacing is all wrong and plotmath() seems to have no 
way to do kernning or overprinting.  I'm surprised Paul didn't 
generalize the hat()-type functionality.

ggplot(data, aes(x=X)) + geom_line(aes(y = Z), size=0.43) +
   xlab(expression(atop("\U0308",Omega)))

ggplot(data, aes(x=X)) + geom_line(aes(y = Z), size=0.43) +
   xlab(expression(atop("\U0308",omega)))


On 5/14/2017 11:18 AM, Ranjan Maitra wrote:
> On Sun, 14 May 2017 09:08:46 -0700 David Winsemius <dwinsemius at comcast.net> wrote:
>
>>> 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.
>
> Thanks! I was trying to avoid using tikz but I guess that there may well be no other alternative.
>
> Best wishes,
> Ranjan
>
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