[Rd] key-value mapping in C inside R?

Simon Urbanek simon.urbanek at r-project.org
Thu Dec 30 19:16:59 CET 2010

On Dec 30, 2010, at 11:25 AM, Matteo Bertini wrote:

> Il giorno 30/dic/2010, alle ore 16.03, Simon Urbanek ha scritto:
>> On Dec 30, 2010, at 7:50 AM, Matteo Bertini wrote:
>>> I'm testing some modifications in arima.c.
>>> I've noticed that a big internal array of double (rbar) is usually sparse and I'd like to add an option to store it as key-value mapping.
>>> Is there a library function or some other approach already used inside the R core for key-value mappings?
>> environment created with hash=TRUE, e.g.:
>> e = new.env(TRUE, emptyenv())
>> e[["foo"]] = "bar"
>> You can even set "size" with the expected size if you know it in advance.
> Interesting, but is it possible to use this from the C code?

Sure, assignment:
void defineVar(SEXP symbol, SEXP value, SEXP rho)
SEXP findVarInFrame(SEXP rho, SEXP symbol)

so the above assignment would be in C
defineVar(install("foo"), mkString("bar"), env)
where env is the environment created above.


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