R help - Jun 2011 - plotmath: paste string and expression [from a vector of expressions]

Dear all,

I have a vector of expressions and would like to "paste" some string
to it before using it in a plot:

vars <- vector("expression", 2)
vars[1] <- expression(alpha)
vars[2] <- expression(beta)
plot(0, 0, main=substitute(bold("Foo" ~~ VAR), list(VAR=vars[2]) ))

Although I tried hard, I just can't figure out how to solve this. The title
should be "Foo <theta>", where <theta> is the greek
letter. I tried some constructions with bquote but that wasn't successful...
I also looked in the mailing list but couldn't find anything helpful [I am
sure I overlooked something].

Cheers,

Marius

On 02.06.2011 20:43, Marius Hofert wrote:
> Dear all,
>
> I have a vector of expressions and would like to "paste" some
string to it before using it in a plot:
>
> vars<- vector("expression", 2)
> vars[1]<- expression(alpha)
> vars[2]<- expression(beta)
> plot(0, 0, main=substitute(bold("Foo" ~~ VAR), list(VAR=vars[2])
))
>
> Although I tried hard, I just can't figure out how to solve this. The
title should be "Foo<theta>", where<theta>  is the greek
letter. I tried some constructions with bquote but that wasn't successful...
I also looked in the mailing list but couldn't find anything helpful [I am
sure I overlooked something].

plot(0, 0, main=expression("Foo" ~~ theta))

Uwe Ligges


> Cheers,
>
> Marius
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

Hi:

This seems to work:

vars2 <- c(quote(alpha), quote(beta))   # returns a list of mode call
plot(0, 0, main = bquote(bold('Foo '~.(vars2[[2]]))))

Expressions are only evaluated once, which means that inner
expressions are not evaluated. You need a call object rather than an
expression inside of bquote().

HTH,
Dennis

On Thu, Jun 2, 2011 at 11:43 AM, Marius Hofert <m_hofert at web.de>
wrote:
> Dear all,
>
> I have a vector of expressions and would like to "paste" some
string to it before using it in a plot:
>
> vars <- vector("expression", 2)
> vars[1] <- expression(alpha)
> vars[2] <- expression(beta)
> plot(0, 0, main=substitute(bold("Foo" ~~ VAR), list(VAR=vars[2])
))
>
> Although I tried hard, I just can't figure out how to solve this. The
title should be "Foo <theta>", where <theta> is the greek
letter. I tried some constructions with bquote but that wasn't successful...
I also looked in the mailing list but couldn't find anything helpful [I am
sure I overlooked something].
>
> Cheers,
>
> Marius
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>