[R] Conversion of strings to expressions
Prof Brian Ripley
ripley at stats.ox.ac.uk
Thu Nov 4 16:42:16 CET 2004
?get
> vec<-c(1,2,3,2)
> get("vec") == 2
[1] FALSE TRUE FALSE TRUE
Note that this is converting a string to an object, not to an expression:
the latter is done by
> parse(text="vec")
expression(vec)
On Thu, 4 Nov 2004, Alexander Sokol wrote:
> I'm not sure how to state my question in a technically accurate manner, so
> I'll use a short example to clarify my problem:
>
> Say I have a vector,
>
> vec<-c(1,2,3,2)
>
> I would like to be able to "reference" the vector by using the string
> containing the name of the vector - that is, I would like to know of some
> function which is able to convert the string "vec" into the vector vec itself.
> The purpose of this is to be able to do something like
>
> >somefunc("vec")==2
> [1] FALSE TRUE FALSE TRUE
>
> I hope it is clear from this what the problem is. It seems to me that the
> function desired is akin to a sort of "inverse" to the quote() function, but I
> have been unable to find such a function.
>
> I am using R 1.9.1 on Windows 2000 SP4. Does anyone have a suggestion of how
> to solve the problem?
--
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
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