Special character is graph label

You do this with plotmath (see the manual page, ?plotmath):

plot(rnorm(10), rnorm(10), xlab=expression(bar(X)))

-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352


-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Robert U
Sent: Wednesday, May 6, 2015 8:10 AM
To: R-help at r-project.org
Subject: [R] Special character is graph label

Dear R users,
I am having issues finding a special character (and how to insert it) in the lab of a graph axis. 

Let us say that the label of my axis is "X", i would like the X to have a "line" over it, indicating that it is the "mean of X values" (i don't even know how to properly state that in english...). Does someone understand, and have any idea about how to do that?
Greetings,
R.H


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