Re: [Rd] Modifying parsed code

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Fri 07 Jul 2006 - 13:03:01 GMT

On Fri, 7 Jul 2006, hadley wickham wrote:

> I would like to take this:
>
> .img(plot(1:10), filename="a")

I presume from your title that you want to take

foo <- parse(text='.img(plot(1:10), filename="a")')

? That's an expression. In which case

> foo[[1]][[2]]

plot(1:10)

(first expression which a call, and calls are symbol, arg1, arg2 ...).

>
> and produce
>
> plot(1:10)
>
> ie. whenever .img is used, I want to take the first argument and throw
> away everything else.
>
> (I am trying to produce a Sweave like environment in which I can apply
> certain functions, but not have them displayed in the output)
>
> I think I should be able to do it using substitute, but I don't know
> how to operate on language objects. Any hints would be appreciated.
>
> Thanks,
>
> Hadley
>
> ______________________________________________
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> https://stat.ethz.ch/mailman/listinfo/r-devel
>
>

-- 
Brian D. Ripley,                  ripley@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

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