[R] sub- and superscript in plot labels

[Gavin Simpson]

Gavin Simpson wrote:
> Dear List,
> 
> I need to add a subscript and a superscript to some of the ions in the 
> labels on some plots.
> 
> I have got to here but now I'm stuck:
> 
> plot(1:10, xlab = expression(paste("nm SO"[4], " ", mu, "eq cm"^{-2}, " 
> yr"^{-1})))
> 
> Which gives almost  what I require. No matter what I tried, however, I 
> could not get bot a sub script *and* a superscript attached to the SO in 
> the label.
> 
> In LaTeX I would just do $SO_4^{2-}$ but taking that to R produces a 
> syntax error:
> 
> plot(1:10, xlab = expression(paste("nm SO"[4]^{2-}, " ", mu, "eq 
> cm"^{-2}, " yr"^{-1})))
> 
> Strangely, I can do this:
> 
> plot(1:10, xlab = expression(paste("nm SO"[4]^2, " ", mu, "eq cm"^{-2}, 
> " yr"^{-1})))
> 
> With almost the desired effect (except I need to add two characters to 
> the superscript).
> 
> Can any one offer a solution?
> 
> Many thanks
> 
> Gavin

With further playing around, it would appear that you can sort of 
achieve what I was looking for by changing the ordering of the 
characters in the braces on the superscript:

plot(1:10, xlab = expression(paste("nm SO"[4]^{-2}, " ", mu, "eq
cm"^{-2}, " yr"^{-1})))

which works as required.

Is this intentional behaviour? My original question still stands, 
however, is there a way to have {2-} appear as the superscript?

The forgotten version info (sorry!):

 > version
          _
platform i686-pc-linux-gnu
arch     i686
os       linux-gnu
system   i686, linux-gnu
status   Patched
major    2
minor    0.0
year     2004
month    10
day      25
language R

Running on Fedora Core 2.

Many thanks

Gavin
-- 
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Gavin Simpson                     [T] +44 (0)20 7679 5522
ENSIS Research Fellow             [F] +44 (0)20 7679 7565
ENSIS Ltd. & ECRC                 [E] gavin.simpson at ucl.ac.uk
UCL Department of Geography       [W] http://www.ucl.ac.uk/~ucfagls/cv/
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