[Rcpp-devel] Eigen-like pointer mappings in Rcpp?

Sparapani, Rodney rsparapa at mcw.edu
Wed Feb 18 00:12:43 CET 2015

On Tue, 2015-02-17 at 15:57 -0500, Yixuan Qiu wrote:
> Hello Rodney,
> If all you need is to pass a pointer to the fit() function (assuming
> fit() does not modify x) and get the result a, you do not need to make
> a copy. Simply wrap _x by a NumericVector and call the data() method.
> Rcpp::NumericVector x(_x);
> double a = fit(x.data(), n);
> You can even directly use the R API without creating an Rcpp object.
> double a = fit(REAL(_x), n);
> Best,
> Yixuan

Hi Yixuan:

That's exactly what I wanted!  However, I can't seem to find that method 
at http://dirk.eddelbuettel.com/code/rcpp/html

Can you please point me to it?

From this...

Rcpp::NumericVector x(_x);

double a = fit(x.data(), n);

I get...

error: class Rcpp::NumericVector has no member named data

Am I doing something dumb?

I'm using Rcpp 0.10.3 w/ 2.15.3 R and GCC 4.4.7 if it matters.



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