[R] Multiple expressions, when using substitute()

[Spencer Graves]

	  Have you received a reply to this post?  I couldn't find one, and I 
couldn't find a solution, even though one must exist.  I can get the 
substitute to work in "main" but not "legend":

B <- 2:3
eB <- substitute(y==a*x^b, list(a=B[1], b=B[2]))
plot(1:2, 1:2, main=eB)

	  You should be able to construct it using "mtext", but I couldn't get 
the desired result using legend.

	  hope this helps.
	  spencer graves

John Maindonald wrote:

> expression() accepts multiple expressions as arguments, thus:
> 
> plot(1:2, 1:2)
> legend("topleft",
>                expression(y == a * x^b,
>                                     "where "* paste(y=="wood; ",  
> x=="dbh")))
> 
> Is there a way to do this when values are to be substituted
> for a and b? i.e., the first element of the legend argument
> to legend() becomes, effectively:
>    substitute(y == a * x^b, list(a = B[1], b=B[2]))
> 
> John Maindonald             email: john.maindonald at anu.edu.au
> phone : +61 2 (6125)3473    fax  : +61 2(6125)5549
> Centre for Bioinformation Science, Room 1194,
> John Dedman Mathematical Sciences Building (Building 27)
> Australian National University, Canberra ACT 0200.
> 
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