Hi:

1. expression() in plotmath ignores control characters such as \n.
2. The workaround, discussed a couple of times on this list (hence in the
archives), is to use the atop function, so try something like

plot(0:1,0:1,xaxt="n")
axis(side=1,at=.3,expression(paste("IFN-", gamma, "\n", "TNF-", alpha)))
axis(side=1,at=.6,expression(atop("a label", "2nd line")))

It appears you'll have to make some vertical adjustments, but that's the
basic workaround.

HTH,
Dennis

On Tue, Mar 1, 2011 at 11:32 AM, Daryl Morris <darylm@uw.edu> wrote:

> Hello,
>
> I am trying to write math-type on a plot.  Due to space limitations on the
> plot, I want 2 short expressions written on top of each other.  It is
> certainly possible to write them in two separate calls, but that involves
> fine-tuning locations and a lot of trial and error (and I'm trying to write
> a general purpose function).
>
> Here's where I've gotten to:
> plot(0:1,0:1,xaxt="n")
> axis(side=1,at=.3,expression(paste("IFN-", gamma, "\n", "TNF-", alpha)))
> axis(side=1,at=.6,"a label\n2nd line")
>
> What I am trying to do is illustrated by the the non-expression axis label
> ("a label\n2nd line").  The "\n" forces a new line when I'm not using
> expressions, but doesn't work for my real example.
>
> I have googled for general documentation on expressions, but the only thing
> I've been able to find is the help for plotmath(), so if someone can point
> me to more complete documentation that would also be helpful.
>
> thanks, Daryl
> SCHARP, FHCRC, UW Biostatistics
>
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