[R] Plotmath issue superscript "-"

[Peter Dalgaard]

Gavin Simpson wrote:
> Dear List,
>
> I'm trying to typeset some chemical ions in axis labels. These have both
> super and subscript components, and for some, I need a superscript "-".
> In LaTeX I might use $NO_3^-$ to do the typesetting, but I'm having a
> problem getting the correct invocation for expression:
>
>   
>> expression(NO^{-}[3])
>>     
> Error: syntax error, unexpected '}' in "expression(NO^{-}"
>   
>> expression(NO^-[3])
>>     
> Error: syntax error, unexpected '[' in "expression(NO^-["
>   
>> expression(NO^-)
>>     
> Error: syntax error, unexpected ')' in "expression(NO^-)"
>   
>> expression(NO^{-})
>>     
> Error: syntax error, unexpected '}' in "expression(NO^{-}"
>
> This is with R 2.5.1 (exact version info below).
>
> I suspect this is something to do with my use of the "-", which has some
> special meaning.
>
> Is there a way to achieve a superscript "-" (or similar looking
> character) using the plotmath routines in R?
>
>   
It's an operator, it needs something to operate on.

Try

 plot(0,main=quote(NO^-{}))



> Thanks in advance,
>
> G
>
>   
>> version
>>     
>                _                                          
> platform       i686-pc-linux-gnu                          
> arch           i686                                       
> os             linux-gnu                                  
> system         i686, linux-gnu                            
> status         Patched                                    
> major          2                                          
> minor          5.1                                        
> year           2007                                       
> month          07                                         
> day            05                                         
> svn rev        42131                                      
> language       R                                          
> version.string R version 2.5.1 Patched (2007-07-05 r42131)
>
>   


-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907