Re: [R] Multiple expressions, when using substitute()

From: Spencer Graves <spencer.graves_at_pdf.com>
Date: Tue 11 Oct 2005 - 11:41:37 EST

          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@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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-- 
Spencer Graves, PhD
Senior Development Engineer
PDF Solutions, Inc.
333 West San Carlos Street Suite 700
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spencer.graves@pdf.com
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Received on Tue Oct 11 11:46:01 2005

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