R help - Oct 2009 - How do I wrap a long mixed text/math expression in an axis label?

I would like to wrap a y-axis label onto two lines. My label is an expression
containing both text and math symbols. I have looked at plotmath,
strsplit(), strwrap(), deparse(), do.call(), substitute() and bquote().
Based on previous posts, I can get plain text to wrap. However, when I try
these methods on my label, the exact string is returned, rather than
evaluating the math symbols.

My starting point:

x<-c(1:10)
y<-seq(5,50,5)
par(mar=c(6,6,6,1),cex.lab=1.3,cex.axis=1.2)
plot(x,y, xlab=NA, ylab=expression(paste("Saturating Irradiance,
",E[k],",
",mu,"mol photons ", m^-1," ", s^-1)))

An unsuccessful example:

plot(x,y, xlab=NA, ylab=strwrap(expression(paste("Saturating Irradiance,
",E[k],", ",mu,"mol photons ", m^-1," ",
s^-1)), width=26))

I've tried so many iterations that I have thoroughly confused myself! I
would appreciate any input on how to get the expression to wrap on two (or
more, if I had a really long label) lines. I am using R version 2.9.2
(2009-08-24) on a Mac running OS X 10.5.8.

Many thanks for your time.
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On 10/19/2009 5:28 AM, Cheryl Squair wrote:
> I would like to wrap a y-axis label onto two lines. My label is an
expression
> containing both text and math symbols. I have looked at plotmath,
> strsplit(), strwrap(), deparse(), do.call(), substitute() and bquote().
> Based on previous posts, I can get plain text to wrap. However, when I try
> these methods on my label, the exact string is returned, rather than
> evaluating the math symbols.
You can't really get plotmath to wrap, as far as I know, but you can 
manually split a label to go onto two lines using atop.  For example, 
with your setup I don't think your margins are big enough, but the 
following seems to work:

par(mar=c(6,8,6,1),cex.lab=1.3,cex.axis=1.2)
plot(x,y, xlab=NA, ylab=expression(atop(paste("Saturating Irradiance,
",
E[k], ",",mu,"\nmol"), paste(" photons ",
m^-1," ", s^-1))))

Duncan Murdoch
> 
> My starting point:
> 
> x<-c(1:10)
> y<-seq(5,50,5)
> par(mar=c(6,6,6,1),cex.lab=1.3,cex.axis=1.2)
> plot(x,y, xlab=NA, ylab=expression(paste("Saturating Irradiance,
",E[k],",
> ",mu,"mol photons ", m^-1," ", s^-1)))
> 
> An unsuccessful example:
> 
> plot(x,y, xlab=NA, ylab=strwrap(expression(paste("Saturating
Irradiance,
> ",E[k],", ",mu,"mol photons ", m^-1," ",
s^-1)), width=26))
> 
> I've tried so many iterations that I have thoroughly confused myself! I
> would appreciate any input on how to get the expression to wrap on two (or
> more, if I had a really long label) lines. I am using R version 2.9.2
> (2009-08-24) on a Mac running OS X 10.5.8.
> 
> Many thanks for your time.