[Rcpp-devel] 'Nested' Rcpp functions using inline

[Jeffrey Pollock]

I think you need to use the `includes` argument of cxxfunction to include a
pure c++ function ie;

library(inline)
library(Rcpp)

inc <-'
        int fun1(double x, double y) {
            return (exp(x) - y) > 0 ? 1 : 0;
        }
        '

body <-'
        NumericVector u   = as<NumericVector>(u_r);
        double        mu  = as<double>(mu_r),
        v   = log(mu);
        int           n   = u.size(),
        res = 0;

        for(int i=0; i<n; i++){
            res += fun1(u(i), v);
        }

        return wrap(res);
        '

fun.test <- cxxfunction(signature(u_r = 'numeric', mu_r = 'numeric'), body,
"Rcpp", inc)

> identical(fun.test(1:4, 100), sum(exp(1:4) > log(100)))
[1] TRUE

On Wed, Oct 10, 2012 at 3:39 PM, Rubem Kaipper Ceratti <
rubem_ceratti at yahoo.com.br> wrote:

> Hi,
>
> I'm currently using Rcpp and inline to speed up some R code I wrote, but
> being a C++/Rcpp newbie I'm running into some difficulties. More
> specifically, I'm having problems calling an Rcpp function inside another
> one. As a toy example consider the code:
> ##
> library(Rcpp)
> library(inline)
>
> code2.0 <-'
>   NumericVector u   = as<NumericVector>(u_r);
>   double        mu  = as<double>(mu_r),
>                 v   = log(mu);
>   int           n   = u.size(),
>                 res = 0;
>
>   for(int i=0; i<n; i++){
>     res += (exp(u(i))-v) > 0 ? 1 : 0;
>   }
>
>   return wrap(res);
> '
> sig2 <- signature(u_r = 'numeric', mu_r = 'numeric')
> fun.test <- cxxfunction(sig2, code2.0, plugin = "Rcpp")
>
> fun.test(1:4, 100)
> sum(exp(1:4) > log(100))  # ok!
> ##
>
> It works just fine. Now, I'd like to break it down into two functions like
> so:
> ##
> code1 <-'
>   double x = as<double>(x_r),
>          y = as<double>(y_r),
>          ans;
>
>   ans = (exp(x)-y) > 0 ? 1 : 0;
>
>   return wrap(ans);
> '
>
> code2.1 <-'
>   NumericVector u   = as<NumericVector>(u_r);
>   double        mu  = as<double>(mu_r),
>                 v   = log(mu);
>   int           n   = u.size(),
>                 res = 0;
>
>   for(int i=0; i<n; i++){
>     res += as<int>(fun1(u(i),v));
>   }
>
>   return wrap(res);
> '
>
> sig1 <- signature(x_r = 'numeric', y_r = 'numeric')
> sig2 <- signature(u_r = 'numeric', mu_r = 'numeric')
> fun.test <- cxxfunction(list(fun1 = sig1, fun2 = sig2),
>                         list(code1, code2.1), plugin = "Rcpp")
> ##
>
> But I get the error message:
> # file5686a0c71e8.cpp: In function 'SEXPREC* fun2(SEXP, SEXP)':
> #   file5686a0c71e8.cpp:52:33: error: invalid cast from type 'double' to
> type 'SEXP'
> # file5686a0c71e8.cpp:55:20: error: invalid cast from type
> 'Rcpp::traits::storage_type<14>::type {aka double}' to type 'SEXP'
>
> I then tried to change the types of 'u(i)' and 'v' to SEXP, but I get the
> same error:
> ##
> code2.2 <-'
>   NumericVector u   = as<NumericVector>(u_r);
>   double        mu  = as<double>(mu_r),
>                 v   = log(mu);
>   int           n   = u.size(),
>                 res = 0;
>   SEXP          us, vs = (SEXP) v;
>
>   for(int i=0; i<n; i++){
>     us = (SEXP) u(i);
>     res += as<int>(fun1(us,vs));
>   }
>
>   return wrap(res);
> '
>
> fun.test <- cxxfunction(list(fun1 = sig1, fun2 = sig2),
>                         list(code1, code2.2), plugin = "Rcpp")
> ##
> # file5686a0c71e8.cpp: In function 'SEXPREC* fun2(SEXP, SEXP)':
> #   file5686a0c71e8.cpp:52:33: error: invalid cast from type 'double' to
> type 'SEXP'
> # file5686a0c71e8.cpp:55:20: error: invalid cast from type
> 'Rcpp::traits::storage_type<14>::type {aka double}' to type 'SEXP'
>
> Is there any way to make it work?
>
> Thanks,
> Rubem
>
>
>
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