On Wed, Apr 28, 2010 at 5:21 PM, Dennis Fisher <fis...@plessthan.com> wrote:
> Colleagues
>
> I have a lengthy script that calls mtext. Under most circumstances, a
> graphics device is open and a plot exists, in which case mtext works as
> expected. However, there are some instances where the graphics device is
> open but no plot exists. When mtext is called, I receive an error message:
> Error in mtext(1) : plot.new has not been called yet
>
> The solution is to confirm that:
> a. the device is open: length(dev.list()) > 0
> b. whether plot.new has been called.
>
> I need help on the latter - how does one test whether plot.new has been
> called?
You could see if par(new=TRUE) generates a warning:
> par(new=TRUE)
Warning message:
In par(new = TRUE) : calling par(new=TRUE) with no plot
> plot.new()
> par(new=TRUE)
>
- because the help(par) says:
It is an error (ignored with a warning) to try to
use ‘new=TRUE’ on a device that does not currently contain a
high-level plot
To see if a warning happens, set option(warn=2) to turn warnings to
errors, and then wrap the par() call in a try() clause. Or some other
way.
Or you could just wrap your mtext() call in a try clause....
Barry
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