R help - Dec 2009 - Array of legend text with math symbols from predefined variables

Hello,

I am trying to include legend text with math symbols from a predefined
character variable that is read in from a file.
?
If there is only one line of text in the legend, the following, although
cumbersome, works for me:

? > LegendText = " 'U' [infinity], '=10 m/s' "?? #
(read in from a file)
??> LegendName = paste("bquote(paste(",LegendText, "))")
? > plot( c(1,2,3), c(1,2,3) )
? > legend(?topleft?,1, eval(parse(text=LegendName)) ) 

?If I now have more than one line in a plot and hence want to include more
than one line of legendtext, I run into problems because

? > legend(?topleft?,1, c(
?eval(parse(text=LegendName1)),eval(parse(text=LegendName2)) ?) 

will not result in evaluation of the character string but just a paste of
the string and

? > legend(?topleft?,1, eval(parse(text=c(LegendName1, LegendName2))) ?) 

will only evaluate the first element of the array.

Am I trying to do the impossible or is my approach totally wrong? Any help
would be greatly appreciated!

Koen

See

Ligges, U. (2002): R Help Desk: Automation of Mathematical Annotation in 
Plots. R News 2 (3), 32-34.
http://www.r-project.org/doc/Rnews/Rnews_2002-3.pdf

Uwe Ligges

Koen wrote:
> Hello,
> 
> I am trying to include legend text with math symbols from a predefined
> character variable that is read in from a file.
>  
> If there is only one line of text in the legend, the following, although
> cumbersome, works for me:
> 
>   > LegendText = " 'U' [infinity], '=10 m/s' "
# (read in from a file)
>   > LegendName = paste("bquote(paste(",LegendText,
"))")
>   > plot( c(1,2,3), c(1,2,3) )
>   > legend(?topleft?,1, eval(parse(text=LegendName)) ) 
> 
>  If I now have more than one line in a plot and hence want to include more
> than one line of legendtext, I run into problems because
> 
>   > legend(?topleft?,1, c(
>  eval(parse(text=LegendName1)),eval(parse(text=LegendName2))  ) 
> 
> will not result in evaluation of the character string but just a paste of
> the string and
> 
>   > legend(?topleft?,1, eval(parse(text=c(LegendName1, LegendName2)))  )
> 
> will only evaluate the first element of the array.
> 
> Am I trying to do the impossible or is my approach totally wrong? Any help
> would be greatly appreciated!
> 
> Koen
> 
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