[R] QCC and PlotMath question

[Shawn Way]

For some reason, using the qcc package, I'm unable to use the plotmath
notation in the title.  Can anyone see what I'm doing wrong?

library(qcc)
a <- rnorm(100)
qcc(a,type="xbar.one",title=expression(bar(X)),ylab=expression(CFU/ft^3)
)

This seems to not let the expression be evaluated, so I tried:

qcc(a,type="xbar.one",title=eval(expression(bar(X))),ylab=expression(CFU
/ft^3))

And get the following error:
Error in eval(expr, envir, enclos) : couldn't find function "bar"

Any thoughts?

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"Policies are many, Principles are few, Policies will change, Principles
never do." 
-John C. Maxwell


Shawn Way, PE