Slightly nicer version:
--- snip --------------------------------------------------------------------
#include <Rcpp.h>
// [[Rcpp::export]]
Rcpp::DataFrame stevePlot(Rcpp::NumericVector itable) {
size_t cnt = itable.size(), num = 0;
double nth, n1th = 0, n2th = 0, n3th = 0;
double x, y, usex, usey, pha = 0;
std::vector<double> xv, yv;
const double scaling = 0.5;
usex = sin(pha);
usey = cos(pha);
while (num < cnt) {
double x1, y1, z1;
nth = itable[num];
num++;
x1 = (nth - n1th) * scaling;
y1 = (n1th - n2th) * scaling;
z1 = (n2th - n3th) * scaling;
x = (x1*usey+z1*usex);
y = y1 + (z1*usey-x1*usex) / 2;
if (num > 4) {
xv.push_back(x);
yv.push_back(y);
}
n3th=n2th; n2th=n1th; n1th=nth;
}
return(Rcpp::DataFrame::create(Rcpp::Named("X") = xv,
Rcpp::Named("Y") = yv));
}
/*** R
library(ggplot2)
Xin <- runif(10000, min = 0, max = 65535)
Xout <- stevePlot(Xin)
qplot(X, Y, data=Xout)
*/
--- snip --------------------------------------------------------------------
Still just Rcpp::sourceCpp("filenamehere.cpp") it.
Dirk
--
http://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org
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