[R] expression() - Superscript in y-axis, keeping line break in string

[Prof Brian Ripley]

On Fri, 4 Aug 2006, Marc Schwartz (via MN) wrote:

> On Fri, 2006-08-04 at 09:47 -0600, Andrew Kniss wrote:
> > I've tried several different ways to accomplish this, but as yet to no
> > avail.  My y-axis for a plot has a rather long label, and thus I have
> > been using "/n" to break it into two lines.  However, to make it
> > technically correct for publication, I also need to use superscript in
> > the label.  For example:
> > 
> >      par(oma=c(0,0,2,0),mar=c(5,6,0.25,2),lheight=1)
> >      plot(1:10,
> >           ylab="14C-glyphosate line1\n line2")
> > 
> > will provide the text in two lines as I would like it.  However, I am
> > trying to keep those same line breaks when using expression() to get my
> > superscript number.  This will not work, as it aligns the "14C" section
> > with the bottom line of the expression making little sense to the
> > reader.
> > 
> >      par(oma=c(0,0,2,0),mar=c(5,6,0.25,2),lheight=1)
> >      plot(1:10,
> >           ylab=expression(" "^14*C*"-glyphosate line1\n line2"))
> > 
> > Is there a way to align the "14C" portion of the expression with the top
> > line of the string rather than the bottom line?  Any suggestions are
> > greatly appreciated.
> > Andrew
> 
> plotmath, as has been covered many times previously, does not support
> multi-line expressions. A note should probably be added to ?plotmath on
> this.

I've added a note.  I think what is exact is that control chars are not 
interpreted ('expresssion' is an overloaded work in this context).

Thanks for the nudge (and please do continue to make such remarks).

Brian

> 
> Thus, you need to create each line in the label separately:
> 
>   par(oma=c(0,0,2,0),mar=c(5,6,0.25,2),lheight=1)
>   
>   plot(1:10, ylab = "")
> 
>   # Now use mtext() to place each line of the y axis label
> 
>   mtext(2, text = expression(" "^14*C*"-glyphosate line1"), line = 3)
> 
>   mtext(2, text = "line2", line = 2)
> 
> See ?mtext for more information.
> 
> HTH,
> 
> Marc Schwartz
> 
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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