R help - Jan 2008 - multiple text placements and expressions revisited

Hi all,

I asked something like this earlier but decided that a proper minimal
example might be helpfull ;0)

Why does this work with regards to the expression (substitution):

require(stats)
plot(cars)
text(5,120,labels=substitute(i^{z+phantom()}*"("*a*"
AMU)",list(i="yx",z=2,a=0)))
text(c(5,5),c(115,110),labels=c("One","Two"))

But adding this (using a vector of expressions/substitutions) fails to print
the expression correctly:

text(c(5,5),c(105,100),labels=c(substitute(i^{z+phantom()}*"("*a*"
AMU)",list(i="yx",z=2,a=0)),"Three"))

This is a bug, no?

Joh

On Thu, 17 Jan 2008, Johannes Graumann wrote:
> Hi all,
>
> I asked something like this earlier but decided that a proper minimal
> example might be helpfull ;0)
>
> Why does this work with regards to the expression (substitution):
>
> require(stats)
> plot(cars)
> text(5,120,labels=substitute(i^{z+phantom()}*"("*a*"
> AMU)",list(i="yx",z=2,a=0)))
> text(c(5,5),c(115,110),labels=c("One","Two"))
>
> But adding this (using a vector of expressions/substitutions) fails to
print
> the expression correctly:
>
>
text(c(5,5),c(105,100),labels=c(substitute(i^{z+phantom()}*"("*a*"
> AMU)",list(i="yx",z=2,a=0)),"Three"))
>
> This is a bug, no?
Yes, but not where you appear to think it is.

'labels' is not an expression: check it by typeof(). Using expression()
in
place of c() will give what I think you intended.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595