[R] evaluating R expressions from C

[Uwe Ligges]

Iryna Lobach wrote:
> 
> Hello!
> 
> I've looked at R help and previous postings, but I am not sure I
> completely understand the mechanism of evaluating R expressions from C++.

C or C++ (the latter is a bit more tricky)?
Have you read the manual "Writing R Extensions"? 


> They have function
> 
> SEXP eval(SEXP expr, SEXP rho),
> 
> but I can't get it to work.
> 
> Could anyone who used it give any comments on how efficient it is and,
> if possible, give example of how to use it. My main problem is that I
> don't really understand how pass the name of  R-function and it's
> parameters.

See Section 4.9, "Evaluating R expressions from C", of the manual
"Writing R Extension". There is an example just after the line you gave
above.

Re efficiency: In most circumstances it is faster than in R itself (if
not, nobody would like to do it in C!). As always, it depends on your
problem ...

Uwe Ligges



> Thank you,
> Iryna
> 
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