[R] plotmath: paste string and expression [from a vector of expressions]

[Marius Hofert]

Dear Dennis, Dear Uwe, Dear David,

many thanks for helping. Dennis and David, your solutions seemed perfectly fine, but when I applied it to my original problem, it did not show a title. Below is a (longer) minimal example (the first part is from the help page of bbmle). Is this a bug in bbmle? Hmmm...

library(bbmle)

x <- 0:10
y <- c(26, 17, 13, 12, 20, 5, 9, 8, 5, 4, 8)
d <- data.frame(x,y)

## in general it is best practice to use the `data' argument,
##  but variables can also be drawn from the global environment
LL <- function(ymax=15, xhalf=6)
    -sum(stats::dpois(y, lambda=ymax/(1+x/xhalf), log=TRUE))

## uses default parameters of LL
(fit <- mle2(LL))
ml <- mle2(LL, fixed=list(xhalf=6))
mlp <- profile(ml)
 
vars <- c(quote(theta), quote(beta))
plot(mlp, main=bquote(bold("Foo"~.(vars[[2]]))))

Cheers,

Marius

On 2011-06-02, at 22:23 , Dennis Murphy wrote:

> 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
>> 
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