Hi,
I want to use a random generator that is not available in the Rcpp: rvm
from R's CircStats package and I want the number generated to be the
same as the equivalent function in R. Importing the function within a
Rcpp inline function works fine except if you have an if-else statement.
The strange thing is that it works as long at the if-statement is TRUE,
and then it doens't work anymore and some numbers are repeated but not
in the same order.
Here is an example:
suppressMessages(library(CircStats))
suppressMessages(library(inline))
ft <- '
Rcpp::NumericVector xc(clone(x));
Rcpp::Function vmc(vm);
int n = xc.size();
NumericVector y(n);
RNGScope Scope;
for(int j=0; j<n; j++){
if(xc[j] == 0){
y[j] = as<double>(runif(1,0,2*PI));
}else{
y[j] = as<double>(vmc(1,0,1));
}
}
return y;'
ftt <- cxxfunction(signature( x ="numeric", vm = "function"),
body = ft, plugin = "Rcpp")
ftr <- function(x){
n <- length(x)
y <- numeric(n)
for(i in 1:n){
if(x[i] == 0){
y[i] = runif(1,0,2*pi)
}else{
y[i] = rvm(1, 0, 1)
}
}
return(y)
}
x <- c(0,0,0,1,1,1,0,0,0)
set.seed(9)
r1 <- ftt(x,rvm)
set.seed(9)
r2 <- ftr(x)
cbind(x,r1,r2)
Any idea what my be causing the difference between R and Rcpp? Many
thanks in advance!
Marie
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