Allow Rcpp functions in DEoptim for R

Question

I have been using DEoptim for some time to test different parameters for a hydrology algorithm. The code is mainly written in R, but there is a function written in Rcpp. If I run DEoptim in non-parallel mode, it runs fine, but if I run in parallel mode (ie paralleltype=1) the code returns an error saying it can't find my Rcpp function. So the Rcpp function looks like this:

loadcppfunctions <- function() {
eastfunc <<- 'NumericMatrix eastC(NumericMatrix e, NumericMatrix zerocolmatrix, NumericMatrix zerorowmatrix) {
int ecoln = e.ncol();
int ecolnlessone = ecoln - 1;
int erown = e.nrow();
int erownlessone = erown - 1;

NumericMatrix eout(e.nrow(),e.ncol()) ;
for (int j = 0;j < ecoln;j++) {
if (j > 0) {
eout(_,j) = e(_,j-1);
} else {
eout(_,j) = e(_,0);
}
}
eout(_,0) = zerocolmatrix(_,0);
return eout;
}'
eastC <<- cppFunction(eastfunc)
}

and then I just use:

loadcppfunctions()

Later in the code I call this function as follows:

movefdrerunoff <- eastC(fdrerunoff, zerocolmatrix, zerorowmatrix)

As I say, it all works fine - but if I run DEoptim as follows:

ans <- DEoptimone(Calibrate,lower,upper,DEoptim.control(trace=TRUE,parallelType=1,parVar=c(parVarnames),packages=c("raster","rgdal","maptools","matrixcalc","Rcpp","RcppArmadillo")))

It fails saying:

Error in checkForRemoteErrors(val) : 
  7 nodes produced errors; first error: could not find function "eastC"

So how can I make DEoptim see this function when all the other R based functions are fine.

Thanks, Antony Walker

Answer 1

I found that by adding the Rcpp function inside the main DEoptim function (Calibrate) worked. The Calibrate function looked like:

Calibrate <- function(x) {
eastfunc <<- 'NumericMatrix eastC(NumericMatrix e, NumericMatrix zerocolmatrix, NumericMatrix zerorowmatrix) {
int ecoln = e.ncol();
int ecolnlessone = ecoln - 1;
int erown = e.nrow();
int erownlessone = erown - 1;

NumericMatrix eout(e.nrow(),e.ncol()) ;
for (int j = 0;j < ecoln;j++) {
if (j > 0) {
eout(_,j) = e(_,j-1);
} else {
eout(_,j) = e(_,0);
}
}
eout(_,0) = zerocolmatrix(_,0);
return eout;
}'
eastC <<- cppFunction(eastfunc)

cmax <<- x[1]
Cr <<- x[2]
Cl <<- x[3]
Crb <<- x[4]
Clb <<- x[5]
returnflowriver <<- x[6]
returnflowland <<- x[7]
kd <<- x[8]
startyear()
-NashSutcliffe
}

and then running DEoptim as:

ans <- DEoptimone(Calibrate,lower,upper,DEoptim.control(trace=TRUE,parallelType=1,parVar=c(parVarnames),packages=c("raster","rgdal","maptools","matrixcalc","Rcpp","RcppArmadillo","moveCpp")))